//Caluclates total by adding all the orders which were passed and added to the list
private void Button_Click(object sender, RoutedEventArgs e)
{
double total = 0;
foreach (StoreGoods items in newItemList)
{
total += items.PurchasePrice * items.Quantity;
}
StoreGoods finalOrder = new StoreGoods();
subtotalTxt.Text = "$" + total.ToString();
taxTxt.Text = finalOrder.calculateTax(total).ToString();
grandTotalTxt.Text = finalOrder.calculateGrandTotal(total).ToString();
}
