Round totals for currencies

Rounding is complex because different currencies use different numbers of decimal places.

The following methods return a value with the correct number of decimals, which is determined by the input currency.

• Currency.Round()
• Currency.Percentage()
• Money.Round()

Do not use Math.Round() for rounding. For example, do not use the following code.

var currentCurrency = “JPY” 
    Money itemPrice = new Money(Math.Round(lineItem.ListPrice, 2), currentCurrency);

If you currently use Math.Round, replace it like this.

var currentCurrency = “JPY”
    Money itemPrice = new Money(lineItem.ListPrice, currentCurrency).Round();

Calculate and round an order total

After rounding, use the rounded value for all further totals. For example, here is the correct way to add a number.

var billingCurrency = order.Currency;
    foreach (var item in order.GetAllLineItems())
      {
        var costWithoutDiscount = billingCurrency.Round(item.PlacedPrice * item.Quantity);
        item.Properties["costWithoutDiscount"] = costWithoutDiscount;
      }

Calculate taxes

To get an order‘s correctly-rounded tax amount, do not use the tax amount of individual items. Instead, follow this example.

var billingCurrency = order.Currency;
    var saleTaxesAmount = taxes
      .Where(x => x.TaxType == TaxType.SalesTax)
      .Sum(x => billingCurrency.Percentage(itemPriceWithoutTax, x.Percentage));

In the above code, saleTaxesAmount is returned with a rounded value.

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Note

Do not use billingCurrency.Percentage(itemPriceWithoutTax, x.Percentage) in other situations