private void UpdateTotalPayment(double price)
{
double totalPayment = 0;
double.TryParse(bunifuMetroTextbox_GrandTotal.Text, out totalPayment);
totalPayment += price;
if (bunifuCheckbox_VIPChecker.Checked == true)
{
totalPayment -= totalPayment * ParameterManager.GetVIPDiscount() / 100;
}
bunifuMetroTextbox_GrandTotal.Text = totalPayment.ToString();
UpdateChargedMoney();
}