/// <summary>
        /// payment and customer type button stores the user data input check box,
        /// then redirects the user to the calculator form
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void PaymentAndCustomerTypeButton_Click(object sender, EventArgs e)
        {
            // Stores payment type in GlobalUtilities
            for (int i = 0; i < paymentTypeCheckBox.CheckedIndices.Count; i++)
            {
                switch (paymentTypeCheckBox.CheckedIndices[i])
                {
                case 0:     // Cash
                    GlobalUtilities.setCashPaymentIdentifier(true);
                    break;

                case 1:     // Credit
                    GlobalUtilities.setCreditPaymentIdentifier(true);
                    break;

                case 2:     // Debit
                    GlobalUtilities.setDebitPaymentIdentifier(true);
                    break;

                case 3:     // Check
                    GlobalUtilities.setCheckPaymentIdentifier(true);
                    break;

                case 4:     // Salary Deduction
                    GlobalUtilities.setSalaryDeductionPaymentIdentifier(true);
                    break;
                }
            }

            // Stores customer type in GlobalUtilities
            GlobalUtilities.setCustomerType(customerTypeGroupBox.Controls.OfType <RadioButton>().SingleOrDefault(n => n.Checked == true).Text);

            this.Close();
            PaymentCalculator paymentCalculator = new PaymentCalculator();

            paymentCalculator.ShowDialog();
        }