private void submitButton_Click(object sender, EventArgs e)
        {
            try
            {
                if (_salesList.Count > 0)
                {
                    _sales.CustomerId = _customerId;

                    _sales.GrandTotal     = _grandTotal;
                    _sales.Discount       = _discountPercent;
                    _sales.DiscountAmount = _discountAmount;
                    _sales.PayableAmount  = _payableAmount;

                    foreach (Sales sales in _salesList)
                    {
                        _salesManager.DecreaseProductQuantity(sales);
                    }

                    Add(_sales);

                    //ResetAll();
                    confirmationLabel.Text = "Sales complete for Customer: " + _sales.Customer;
                }
            }
            catch (Exception error)
            {
                ExceptionMessage(error);
            }
        }