public void CalculateTax(ITaxableItem taxableItem, IRetailTransaction retailTransaction)
{
var codes = GetTaxCodes(taxableItem);
LineTaxResult lineTaxResult = new LineTaxResult
{
HasExempt = false,
TaxRatePercent = decimal.Zero,
TaxAmount = decimal.Zero,
ExemptAmount = decimal.Zero
};
foreach (TaxCode code in codes)
{
lineTaxResult.TaxAmount += code.CalculateTaxAmount(codes);
// sum up the amounts that are exempt
if (code.Exempt)
{
lineTaxResult.HasExempt = true;
lineTaxResult.ExemptAmount += lineTaxResult.TaxAmount;
}
}
// Set the 'virtual tax rate', if extended price is ZERO, then just add the full amount
decimal extendedPrice = (taxableItem.Price * Math.Abs(taxableItem.Quantity));
if (extendedPrice == decimal.Zero)
{
extendedPrice = decimal.One;
}
lineTaxResult.TaxRatePercent = ((lineTaxResult.TaxAmount * 100) / extendedPrice);
SetLineItemTaxRate(taxableItem, lineTaxResult);
}
protected static void SetLineItemTaxRate(ITaxableItem taxableItem, LineTaxResult lineTaxResult)
{
// Ignore any portion of the TaxAmount that is 'Exempt' when computing the rate.
decimal amount = lineTaxResult.TaxAmount - lineTaxResult.ExemptAmount;
SetLineItemTaxRate(taxableItem, amount);
}