diff --git a/src/multisafepay/api/paths/orders/order_id/refund/request/components/checkout_data.py b/src/multisafepay/api/paths/orders/order_id/refund/request/components/checkout_data.py
index ae6667c..a5421c4 100644
--- a/src/multisafepay/api/paths/orders/order_id/refund/request/components/checkout_data.py
+++ b/src/multisafepay/api/paths/orders/order_id/refund/request/components/checkout_data.py
@@ -155,7 +155,7 @@ def refund_by_merchant_item_id(
 
         refund_item = found_item.clone()
         refund_item.add_quantity(quantity)
-        refund_item.add_unit_price(found_item.unit_price * -1.0)
+        refund_item.add_unit_price(found_item.unit_price * -1)
 
         self.add_item(refund_item)
 
diff --git a/src/multisafepay/api/paths/orders/order_manager.py b/src/multisafepay/api/paths/orders/order_manager.py
index 38066b4..9ae9092 100644
--- a/src/multisafepay/api/paths/orders/order_manager.py
+++ b/src/multisafepay/api/paths/orders/order_manager.py
@@ -39,6 +39,7 @@
 from multisafepay.api.shared.description import Description
 from multisafepay.client.client import Client
 from multisafepay.util.dict_utils import dict_empty
+from multisafepay.util.json_encoder import DecimalEncoder
 from multisafepay.util.message import MessageList, gen_could_not_created_msg
 from multisafepay.value_object.amount import Amount
 from multisafepay.value_object.currency import Currency
@@ -127,7 +128,7 @@ def create(
         CustomApiResponse: The custom API response containing the created order data.
 
         """
-        json_data = json.dumps(request_order.to_dict())
+        json_data = json.dumps(request_order.to_dict(), cls=DecimalEncoder)
         response: ApiResponse = self.client.create_post_request(
             "json/orders",
             request_body=json_data,
@@ -152,7 +153,7 @@ def update(
         CustomApiResponse: The custom API response containing the updated order data.
 
         """
-        json_data = json.dumps(update_request.to_dict())
+        json_data = json.dumps(update_request.to_dict(), cls=DecimalEncoder)
         encoded_order_id = self.encode_path_segment(order_id)
         response = self.client.create_patch_request(
             f"json/orders/{encoded_order_id}",
@@ -182,7 +183,7 @@ def capture(
         CustomApiResponse: The custom API response containing the capture data.
 
         """
-        json_data = json.dumps(capture_request.to_dict())
+        json_data = json.dumps(capture_request.to_dict(), cls=DecimalEncoder)
         encoded_order_id = self.encode_path_segment(order_id)
 
         response = self.client.create_post_request(
@@ -223,7 +224,7 @@ def refund(
         CustomApiResponse: The custom API response containing the refund data.
 
         """
-        json_data = json.dumps(request_refund.to_dict())
+        json_data = json.dumps(request_refund.to_dict(), cls=DecimalEncoder)
         encoded_order_id = self.encode_path_segment(order_id)
         response = self.client.create_post_request(
             f"json/orders/{encoded_order_id}/refunds",
diff --git a/src/multisafepay/api/shared/cart/cart_item.py b/src/multisafepay/api/shared/cart/cart_item.py
index e8d6279..50ec3b4 100644
--- a/src/multisafepay/api/shared/cart/cart_item.py
+++ b/src/multisafepay/api/shared/cart/cart_item.py
@@ -9,11 +9,15 @@
 
 import copy
 import math
-from typing import Dict, List, Optional
+from decimal import Decimal
+from typing import TYPE_CHECKING, Optional, Type, Union
 
 from multisafepay.exception.invalid_argument import InvalidArgumentException
 from multisafepay.model.api_model import ApiModel
-from multisafepay.value_object.weight import Weight
+from pydantic import validator
+
+if TYPE_CHECKING:
+    from multisafepay.value_object.weight import Weight
 
 
 class CartItem(ApiModel):
@@ -32,7 +36,7 @@ class CartItem(ApiModel):
     product_url: (Optional[str]) The product URL.
     quantity: (Optional[int]) The quantity.
     tax_table_selector: (Optional[str]) The tax table selector.
-    unit_price: (Optional[float]) The unit price.
+    unit_price: (Optional[Decimal]) The unit price as a precise Decimal value.
     weight: (Optional[Weight]) The weight.
 
     """
@@ -43,12 +47,36 @@ class CartItem(ApiModel):
     image: Optional[str]
     merchant_item_id: Optional[str]
     name: Optional[str]
-    options: Optional[List[Dict]]
+    options: Optional[list]
     product_url: Optional[str]
     quantity: Optional[int]
     tax_table_selector: Optional[str]
-    unit_price: Optional[float]
-    weight: Optional[Weight]
+    unit_price: Optional[Decimal]
+
+    @validator("unit_price", pre=True)
+    def convert_unit_price_to_decimal(
+        cls: Type["CartItem"],
+        value: Union[str, float, Decimal, None],
+    ) -> Optional[Decimal]:
+        """
+        Convert unit_price to Decimal for precise monetary calculations.
+
+        Parameters
+        ----------
+        value (Union[str, int, float, Decimal, None]): The value to convert.
+
+        Returns
+        -------
+        Optional[Decimal]: The converted Decimal value or None.
+
+        """
+        if value is None:
+            return None
+        if isinstance(value, Decimal):
+            return value
+        return Decimal(str(value))
+
+    weight: Optional["Weight"]
 
     def add_cashback(self: "CartItem", cashback: str) -> "CartItem":
         """
@@ -149,7 +177,7 @@ def add_name(self: "CartItem", name: str) -> "CartItem":
         self.name = name
         return self
 
-    def add_options(self: "CartItem", options: List[Dict]) -> "CartItem":
+    def add_options(self: "CartItem", options: list) -> "CartItem":
         """
         Add options to the cart item.
 
@@ -216,23 +244,29 @@ def add_tax_table_selector(
         self.tax_table_selector = tax_table_selector
         return self
 
-    def add_unit_price(self: "CartItem", unit_price: float) -> "CartItem":
+    def add_unit_price(
+        self: "CartItem",
+        unit_price: Union[Decimal, float, str],
+    ) -> "CartItem":
         """
-        Add unit price to the cart item.
+        Add unit price to the cart item with precise Decimal conversion.
 
         Parameters
         ----------
-        unit_price: (float) The unit price to be added.
+        unit_price: (Union[Decimal, float, int, str]) The unit price to be added.
 
         Returns
         -------
         CartItem: The updated CartItem instance.
 
         """
-        self.unit_price = unit_price
+        if isinstance(unit_price, Decimal):
+            self.unit_price = unit_price
+        else:
+            self.unit_price = Decimal(str(unit_price))
         return self
 
-    def add_weight(self: "CartItem", weight: Weight) -> "CartItem":
+    def add_weight(self: "CartItem", weight: "Weight") -> "CartItem":
         """
         Add weight to the cart item.
 
@@ -250,10 +284,10 @@ def add_weight(self: "CartItem", weight: Weight) -> "CartItem":
 
     def add_tax_rate_percentage(
         self: "CartItem",
-        tax_rate_percentage: int,
+        tax_rate_percentage: Union[int, Decimal],
     ) -> "CartItem":
         """
-        Add tax rate percentage to the cart item.
+        Add tax rate percentage to the cart item using precise Decimal arithmetic.
 
         This method sets the tax rate percentage for the cart item. The tax rate should be a non-negative number.
 
@@ -263,7 +297,7 @@ def add_tax_rate_percentage(
 
         Parameters
         ----------
-        tax_rate_percentage: (int) The tax rate percentage to be added.
+        tax_rate_percentage: (Union[int, Decimal]) The tax rate percentage to be added.
 
         Returns
         -------
@@ -275,13 +309,17 @@ def add_tax_rate_percentage(
                 "Tax rate percentage cannot be negative.",
             )
 
-        if math.isnan(tax_rate_percentage) or math.isinf(tax_rate_percentage):
+        if isinstance(tax_rate_percentage, float) and (
+            math.isnan(tax_rate_percentage) or math.isinf(tax_rate_percentage)
+        ):
             raise InvalidArgumentException(
                 "Tax rate percentage cannot be special floats.",
             )
 
         try:
-            rating = tax_rate_percentage / 100
+            # Use Decimal for precise division
+            percentage_decimal = Decimal(str(tax_rate_percentage))
+            rating = percentage_decimal / Decimal("100")
             self.tax_table_selector = str(rating)
         except (ValueError, TypeError) as e:
             raise InvalidArgumentException(
@@ -290,9 +328,12 @@ def add_tax_rate_percentage(
 
         return self
 
-    def add_tax_rate(self: "CartItem", tax_rate: float) -> "CartItem":
+    def add_tax_rate(
+        self: "CartItem",
+        tax_rate: Union[Decimal, float],
+    ) -> "CartItem":
         """
-        Add tax rate to the cart item.
+        Add tax rate to the cart item using Decimal for precision.
 
         This method sets the tax rate for the cart item. The tax rate should be a non-negative number.
 
@@ -302,7 +343,7 @@ def add_tax_rate(self: "CartItem", tax_rate: float) -> "CartItem":
 
         Parameters
         ----------
-        tax_rate: (float) The tax rate to be added.
+        tax_rate: (Union[Decimal, float]) The tax rate to be added.
 
         Returns
         -------
@@ -312,12 +353,17 @@ def add_tax_rate(self: "CartItem", tax_rate: float) -> "CartItem":
         if tax_rate < 0:
             raise InvalidArgumentException("Tax rate cannot be negative.")
 
-        if math.isnan(tax_rate) or math.isinf(tax_rate):
+        if isinstance(tax_rate, float) and (
+            math.isnan(tax_rate) or math.isinf(tax_rate)
+        ):
             raise InvalidArgumentException(
                 "Tax rate cannot be special floats.",
             )
 
         try:
+            # Convert to Decimal if not already
+            if not isinstance(tax_rate, Decimal):
+                tax_rate = Decimal(str(tax_rate))
             self.tax_table_selector = str(tax_rate)
         except (ValueError, TypeError) as e:
             raise InvalidArgumentException(
@@ -355,3 +401,10 @@ def from_dict(d: Optional[dict]) -> Optional["CartItem"]:
             return None
 
         return CartItem(**d)
+
+
+# Update forward references to resolve Weight
+# pylint: disable=wrong-import-position
+from multisafepay.value_object.weight import Weight  # noqa: E402
+
+CartItem.update_forward_refs()
diff --git a/src/multisafepay/api/shared/costs.py b/src/multisafepay/api/shared/costs.py
index 510546f..0b721b4 100644
--- a/src/multisafepay/api/shared/costs.py
+++ b/src/multisafepay/api/shared/costs.py
@@ -7,9 +7,11 @@
 
 """Transaction costs model for handling fees and charges in payment processing."""
 
-from typing import Optional
+from decimal import Decimal
+from typing import Optional, Type, Union
 
 from multisafepay.model.api_model import ApiModel
+from pydantic import validator
 
 
 class Costs(ApiModel):
@@ -21,7 +23,7 @@ class Costs(ApiModel):
     transaction_id (Optional[int]): The ID of the transaction.
     description (Optional[str]): The description of the cost.
     type (Optional[str]): The type of the cost.
-    amount (Optional[float]): The amount of the cost.
+    amount (Optional[Decimal]): The amount of the cost as a precise Decimal value.
     currency (Optional[str]): The currency of the cost.
     status (Optional[str]): The status of the cost.
 
@@ -30,10 +32,33 @@ class Costs(ApiModel):
     transaction_id: Optional[int]
     description: Optional[str]
     type: Optional[str]
-    amount: Optional[float]
+    amount: Optional[Decimal]
     currency: Optional[str]
     status: Optional[str]
 
+    @validator("amount", pre=True)
+    def convert_amount_to_decimal(
+        cls: Type["Costs"],
+        value: Union[str, float, Decimal, None],
+    ) -> Optional[Decimal]:
+        """
+        Convert amount to Decimal for precise monetary calculations.
+
+        Parameters
+        ----------
+        value (Union[str, int, float, Decimal, None]): The value to convert.
+
+        Returns
+        -------
+        Optional[Decimal]: The converted Decimal value or None.
+
+        """
+        if value is None:
+            return None
+        if isinstance(value, Decimal):
+            return value
+        return Decimal(str(value))
+
     def add_transaction_id(self: "Costs", transaction_id: int) -> "Costs":
         """
         Add a transaction ID to the Costs instance.
@@ -82,20 +107,26 @@ def add_type(self: "Costs", type_: str) -> "Costs":
         self.type = type_
         return self
 
-    def add_amount(self: "Costs", amount: float) -> "Costs":
+    def add_amount(
+        self: "Costs",
+        amount: Union[Decimal, float, str],
+    ) -> "Costs":
         """
-        Add an amount to the Costs instance.
+        Add an amount to the Costs instance with precise Decimal conversion.
 
         Parameters
         ----------
-        amount (float): The amount of the cost.
+        amount (Union[Decimal, float, int, str]): The amount of the cost.
 
         Returns
         -------
         Costs: The updated Costs instance.
 
         """
-        self.amount = amount
+        if isinstance(amount, Decimal):
+            self.amount = amount
+        else:
+            self.amount = Decimal(str(amount))
         return self
 
     def add_currency(self: "Costs", currency: str) -> "Costs":
diff --git a/src/multisafepay/util/__init__.py b/src/multisafepay/util/__init__.py
index f26e44f..7e664d8 100644
--- a/src/multisafepay/util/__init__.py
+++ b/src/multisafepay/util/__init__.py
@@ -1,7 +1,9 @@
 """Utility functions and helpers for MultiSafepay SDK operations."""
 
+from multisafepay.util.json_encoder import DecimalEncoder
 from multisafepay.util.webhook import Webhook
 
 __all__ = [
+    "DecimalEncoder",
     "Webhook",
 ]
diff --git a/src/multisafepay/util/json_encoder.py b/src/multisafepay/util/json_encoder.py
new file mode 100644
index 0000000..9a6edef
--- /dev/null
+++ b/src/multisafepay/util/json_encoder.py
@@ -0,0 +1,42 @@
+# Copyright (c) MultiSafepay, Inc. All rights reserved.
+
+# This file is licensed under the Open Software License (OSL) version 3.0.
+# For a copy of the license, see the LICENSE.txt file in the project root.
+
+# See the DISCLAIMER.md file for disclaimer details.
+
+"""JSON encoder utilities for API serialization."""
+
+import json
+from decimal import Decimal
+
+
+class DecimalEncoder(json.JSONEncoder):
+    """
+    Custom JSON encoder that converts Decimal objects to float for API serialization.
+
+    This encoder ensures that Decimal values used for precise calculations
+    are properly serialized when sending data to the API.
+    """
+
+    def default(
+        self: "DecimalEncoder",
+        o: object,
+    ) -> object:  # pylint: disable=invalid-name
+        """
+        Convert Decimal to float, otherwise use default encoder.
+
+        Parameters
+        ----------
+        o : object
+            The object to serialize.
+
+        Returns
+        -------
+        object
+            The serialized object (float for Decimal, default for others).
+
+        """
+        if isinstance(o, Decimal):
+            return float(o)
+        return super().default(o)
diff --git a/src/multisafepay/util/total_amount.py b/src/multisafepay/util/total_amount.py
index dae80bf..62c9ce2 100644
--- a/src/multisafepay/util/total_amount.py
+++ b/src/multisafepay/util/total_amount.py
@@ -8,12 +8,43 @@
 """Total amount calculation and validation utilities for order processing."""
 
 import json
+from decimal import Decimal
+from typing import Union
 
 from multisafepay.exception.invalid_total_amount import (
     InvalidTotalAmountException,
 )
 
 
+def _convert_decimals_to_float(
+    obj: Union[Decimal, dict, list, object],
+) -> Union[float, dict, list, object]:
+    """
+    Recursively convert Decimal objects to float for JSON serialization.
+
+    Parameters
+    ----------
+    obj : Union[Decimal, dict, list, object]
+        The object to convert (can be dict, list, Decimal, or any other type)
+
+    Returns
+    -------
+    Union[float, dict, list, object]
+        The converted object with all Decimals replaced by floats
+
+    """
+    if isinstance(obj, Decimal):
+        return float(obj)
+    if isinstance(obj, dict):
+        return {
+            key: _convert_decimals_to_float(value)
+            for key, value in obj.items()
+        }
+    if isinstance(obj, list):
+        return [_convert_decimals_to_float(item) for item in obj]
+    return obj
+
+
 def validate_total_amount(data: dict) -> bool:
     """
     Validate the total amount in the provided data dictionary.
@@ -40,17 +71,22 @@ def validate_total_amount(data: dict) -> bool:
     amount = data["amount"]
     total_unit_price = __calculate_totals(data)
 
-    if (total_unit_price * 100) != amount:
+    # Convert total_unit_price to cents (integer) for comparison
+    total_unit_price_cents = int(total_unit_price * 100)
+
+    if total_unit_price_cents != amount:
         msg = f"Total of unit_price ({total_unit_price}) does not match amount ({amount})"
-        msg += "\n" + json.dumps(data, indent=4)
+        # Create a JSON-serializable copy of data by converting Decimal to float
+        serializable_data = _convert_decimals_to_float(data)
+        msg += "\n" + json.dumps(serializable_data, indent=4)
         raise InvalidTotalAmountException(msg)
 
     return True
 
 
-def __calculate_totals(data: dict) -> float:
+def __calculate_totals(data: dict) -> Decimal:
     """
-    Calculate the total unit price of items in the shopping cart.
+    Calculate the total unit price of items in the shopping cart using precise Decimal arithmetic.
 
     Parameters
     ----------
@@ -58,23 +94,31 @@ def __calculate_totals(data: dict) -> float:
 
     Returns
     -------
-    float: The total unit price of all items in the shopping cart.
+    Decimal: The total unit price of all items in the shopping cart with precise decimal calculation.
 
     """
-    total_unit_price = 0
+    total_unit_price = Decimal("0")
     for item in data["shopping_cart"]["items"]:
         tax_rate = __get_tax_rate_by_item(item, data)
-        item_price = item["unit_price"] * item["quantity"]
-        item_price += tax_rate * item_price
+
+        # Convert to Decimal for precise calculations
+        unit_price = Decimal(str(item["unit_price"]))
+        quantity = Decimal(str(item["quantity"]))
+        tax_rate_decimal = Decimal(str(tax_rate))
+
+        # Calculate item price with tax
+        item_price = unit_price * quantity
+        item_price += tax_rate_decimal * item_price
         total_unit_price += item_price
 
-    return round(total_unit_price, 2)
+    # Round to 2 decimal places for currency
+    return total_unit_price.quantize(Decimal("0.01"))
 
 
 def __get_tax_rate_by_item(
     item: dict,
     data: dict,
-) -> object:
+) -> Union[Decimal, int]:
     """
     Get the tax rate for a specific item in the shopping cart.
 
@@ -85,7 +129,7 @@ def __get_tax_rate_by_item(
 
     Returns
     -------
-    object: The tax rate for the item, or 0 if no tax rate is found.
+    Union[Decimal, int]: The tax rate for the item as Decimal, or 0 if no tax rate is found.
 
     """
     if "tax_table_selector" not in item or not item["tax_table_selector"]:
@@ -103,10 +147,12 @@ def __get_tax_rate_by_item(
             continue
 
         tax_rule = tax_table["rules"][0]
-        return tax_rule["rate"]
-    return (
+        return Decimal(str(tax_rule["rate"]))
+
+    default_rate = (
         data["checkout_options"]["tax_tables"]["default"]["rate"]
         if "default" in data["checkout_options"]["tax_tables"]
         and "rate" in data["checkout_options"]["tax_tables"]["default"]
         else 0
     )
+    return Decimal(str(default_rate)) if default_rate != 0 else 0
diff --git a/src/multisafepay/value_object/unit_price.py b/src/multisafepay/value_object/unit_price.py
index 3d6b67e..85ecb68 100644
--- a/src/multisafepay/value_object/unit_price.py
+++ b/src/multisafepay/value_object/unit_price.py
@@ -7,7 +7,11 @@
 
 """Unit price value object for item pricing in shopping carts."""
 
+from decimal import Decimal
+from typing import Type, Union
+
 from multisafepay.model.inmutable_model import InmutableModel
+from pydantic import validator
 
 
 class UnitPrice(InmutableModel):
@@ -16,19 +20,48 @@ class UnitPrice(InmutableModel):
 
     Attributes
     ----------
-    unit_price (float): The unit price of the item.
+    unit_price (Decimal): The unit price of the item as a precise decimal value.
 
     """
 
-    unit_price: float
+    unit_price: Decimal
+
+    @validator("unit_price", pre=True)
+    def convert_to_decimal(
+        cls: Type["UnitPrice"],
+        value: Union[str, float, Decimal],
+    ) -> Decimal:
+        """
+        Convert the input value to Decimal for precise calculations.
+
+        Parameters
+        ----------
+        value (Union[str, float, Decimal]): The value to convert.
+
+        Returns
+        -------
+        Decimal: The converted Decimal value.
+
+        Raises
+        ------
+        TypeError: If the value cannot be converted to Decimal.
+
+        """
+        if isinstance(value, Decimal):
+            return value
+        if not isinstance(value, (str, float)):
+            raise TypeError(
+                f"Cannot convert {type(value).__name__} to Decimal",
+            )
+        return Decimal(str(value))
 
-    def get(self: "UnitPrice") -> float:
+    def get(self: "UnitPrice") -> Decimal:
         """
         Get the unit price of the item.
 
         Returns
         -------
-        float: The unit price of the item.
+        Decimal: The unit price of the item.
 
         """
         return self.unit_price
diff --git a/tests/multisafepay/integration/api/shared/cart/test_integration_cart_item.py b/tests/multisafepay/integration/api/shared/cart/test_integration_cart_item.py
index 7372bb0..ca39b39 100644
--- a/tests/multisafepay/integration/api/shared/cart/test_integration_cart_item.py
+++ b/tests/multisafepay/integration/api/shared/cart/test_integration_cart_item.py
@@ -8,6 +8,8 @@
 
 """Shared API models and utilities."""
 
+from decimal import Decimal
+
 from multisafepay.api.shared.cart.cart_item import CartItem
 from multisafepay.value_object.weight import Weight
 
@@ -48,7 +50,7 @@ def test_initializes_with_valid_values():
     assert item.quantity == 10
     assert item.tax_table_selector == "standard"
     assert item.tax_rate == 0.2
-    assert item.unit_price == 19.99
+    assert item.unit_price == Decimal("19.99")
     assert item.weight.value == 100
     assert item.weight.unit == "grams"
 
@@ -114,6 +116,6 @@ def test_creates_from_dict():
     assert item.quantity == 10
     assert item.tax_table_selector == "standard"
     assert item.tax_rate == 0.2
-    assert item.unit_price == 19.99
+    assert item.unit_price == Decimal("19.99")
     assert item.weight.unit == "grams"
     assert item.weight.value == 100.0
diff --git a/tests/multisafepay/unit/api/shared/cart/test_unit_cart_item.py b/tests/multisafepay/unit/api/shared/cart/test_unit_cart_item.py
index 1c91bf5..bb85f41 100644
--- a/tests/multisafepay/unit/api/shared/cart/test_unit_cart_item.py
+++ b/tests/multisafepay/unit/api/shared/cart/test_unit_cart_item.py
@@ -103,9 +103,11 @@ def test_adds_tax_table_selector():
 
 def test_adds_unit_price():
     """Test that unit price can be added to a CartItem."""
+    from decimal import Decimal
+
     item = CartItem()
     item.add_unit_price(19.99)
-    assert item.unit_price == 19.99
+    assert item.unit_price == Decimal("19.99")
 
 
 def test_creates_from_empty_dict():
diff --git a/tests/multisafepay/unit/api/shared/test_unit_costs.py b/tests/multisafepay/unit/api/shared/test_unit_costs.py
index 0e1c23e..ac1e91b 100644
--- a/tests/multisafepay/unit/api/shared/test_unit_costs.py
+++ b/tests/multisafepay/unit/api/shared/test_unit_costs.py
@@ -8,6 +8,7 @@
 
 """Unit tests for the shared costs model."""
 
+from decimal import Decimal
 
 from multisafepay.api.shared.costs import Costs
 
@@ -25,7 +26,7 @@ def test_initializes_with_valid_values():
     assert costs.transaction_id == 123
     assert costs.description == "Service Fee"
     assert costs.type == "Fixed"
-    assert costs.amount == 99.99
+    assert costs.amount == Decimal("99.99")
     assert costs.currency == "USD"
     assert costs.status == "Pending"
 
@@ -62,7 +63,7 @@ def test_adds_type():
 def test_adds_amount():
     """Test that an amount is added to a Costs instance."""
     costs = Costs().add_amount(99.99)
-    assert costs.amount == 99.99
+    assert costs.amount == Decimal("99.99")
 
 
 def test_adds_currency():
@@ -91,7 +92,7 @@ def test_creates_from_dict_with_all_fields():
     assert costs.transaction_id == 123
     assert costs.description == "Service Fee"
     assert costs.type == "Fixed"
-    assert costs.amount == 99.99
+    assert costs.amount == Decimal("99.99")
     assert costs.currency == "USD"
     assert costs.status == "Pending"
 
diff --git a/tests/multisafepay/unit/util/test_unit_total_amount.py b/tests/multisafepay/unit/util/test_unit_total_amount.py
index a8e572c..371b21b 100644
--- a/tests/multisafepay/unit/util/test_unit_total_amount.py
+++ b/tests/multisafepay/unit/util/test_unit_total_amount.py
@@ -8,6 +8,8 @@
 
 """Utility functions for test unit total amount."""
 
+from decimal import Decimal
+
 from multisafepay.util.total_amount import (
     validate_total_amount,
     __get_tax_rate_by_item,
@@ -34,7 +36,7 @@ def test_get_tax_rate_by_item():
         },
     }
 
-    assert __get_tax_rate_by_item(item, data) == 0.1
+    assert __get_tax_rate_by_item(item, data) == Decimal("0.1")
 
 
 def test_get_tax_rate_by_item_btw21():
@@ -56,7 +58,7 @@ def test_get_tax_rate_by_item_btw21():
         },
     }
 
-    assert __get_tax_rate_by_item(item, data) == 0.21
+    assert __get_tax_rate_by_item(item, data) == Decimal("0.21")
 
 
 def test_calculate_totals():
@@ -73,7 +75,7 @@ def test_calculate_totals():
         },
     }
 
-    assert __calculate_totals(data) == 2.42
+    assert __calculate_totals(data) == Decimal("2.42")
 
 
 def test_validate_total_amount():
diff --git a/tests/multisafepay/unit/value_object/test_unit_price.py b/tests/multisafepay/unit/value_object/test_unit_price.py
index 6eb4943..af41bbd 100644
--- a/tests/multisafepay/unit/value_object/test_unit_price.py
+++ b/tests/multisafepay/unit/value_object/test_unit_price.py
@@ -8,6 +8,8 @@
 
 """Value object for Test Unit Price data."""
 
+from decimal import Decimal
+
 from pydantic.error_wrappers import ValidationError
 import pytest
 
@@ -17,7 +19,7 @@
 def test_unit_price_initialization():
     """Test the initialization of the UnitPrice object with a valid unit price."""
     unit_price = UnitPrice(unit_price=19.99)
-    assert unit_price.unit_price == 19.99
+    assert unit_price.unit_price == Decimal("19.99")
 
 
 def test_empty_unit_price_initialization():
@@ -29,10 +31,10 @@ def test_empty_unit_price_initialization():
 def test_valid_cast_unit_price_initialization():
     """Test the initialization of the UnitPrice object with a string unit price."""
     unit_price = UnitPrice(unit_price="19.99")
-    assert unit_price.unit_price == 19.99
+    assert unit_price.unit_price == Decimal("19.99")
 
 
 def test_unit_price_get_unit_price():
     """Test the get method of the UnitPrice object."""
     unit_price = UnitPrice(unit_price=19.99)
-    assert unit_price.get() == 19.99
+    assert unit_price.get() == Decimal("19.99")