public decimal CalculateTotal()
        {
            Decimal subTotalAmt = 0.00m;

            foreach (RetailItem item in _cartItems)
            {
                subTotalAmt += item.UnitPrice;
            }

            decimal taxAmt = _taxCalculator.GetTaxAmt(subTotalAmt);

            return(subTotalAmt + taxAmt);
        }