private void RetrieveCart() { if (Session["Cart"] == null) { cart = new ShoppingCart(); PersistCart(cart); } else { using (manager = new ShoppingCartManager()) { cart = (ShoppingCart)Session["Cart"]; if (cart != null) { cart.ITEM_PRICE = manager.CalculateTotal(cart.Items); cart.SalesTax = Math.Round(manager.CalculateSalesTax(cart.ITEM_PRICE), 2); cart.Cost = Math.Round(cart.ITEM_PRICE + cart.SalesTax, 2); } } } }