private void GetPurchasesInCart(string userId)
{
PurchaseModel model = new PurchaseModel();
double subTotal = 0;
List <Purchase> purchaseList = model.GetOrdersInPurchase(userId);
CreateShopTable(purchaseList, out subTotal);
double vat = subTotal * 0.1;
double totalAmount = subTotal + vat + 15;
litTotal.Text = "$ " + subTotal;
litVat.Text = "$ " + vat;
litTotalAmount.Text = "$ " + totalAmount;
}