/// <summary>
        /// Method checks if the value input for monthly sales is a valid number. If is is the number
        /// is converted to a dollar figure else a message is shown that the information
        /// is not valid and the field is cleared.
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void TotalMonthlySalesTextBox_Leave(object sender, EventArgs e)
        {
            double TotalSales;

            if (TotalMonthlySalesTextBox.Text != "")
            {
                try
                {
                    TotalSales = Convert.ToDouble(TotalMonthlySalesTextBox.Text);
                    TotalMonthlySalesTextBox.Text = TotalSales.ToString("C2");
                }
                catch (Exception exception)
                {
                    try
                    {
                        TotalSales = double.Parse(TotalMonthlySalesTextBox.Text, NumberStyles.Currency);
                        TotalMonthlySalesTextBox.Text = TotalSales.ToString("C2");
                    }
                    catch
                    {
                        MessageBox.Show("Invalid Data Entered", "Input Error");
                        Debug.WriteLine(exception.Message);
                        TotalMonthlySalesTextBox.Focus();
                        TotalMonthlySalesTextBox.Text = "";
                        TotalMonthlySalesTextBox.SelectAll();
                    }
                }
            }
        }
        /// <summary>
        /// This method calculates the total sales bonus and displays the total on
        /// the form
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void CalculateButton_Click(object sender, EventArgs e)
        {
            double PercentHoursWorked;
            double TotalHoursWorked;
            double TotalMonthlySales;
            double TotalBonusAmount;
            double SalesBonus;

            try
            {
                TotalHoursWorked   = Convert.ToDouble(TotalHoursWorkedNumericUpDown.Value);
                PercentHoursWorked = TotalHoursWorked / 160;

                TotalMonthlySales = double.Parse(TotalMonthlySalesTextBox.Text, NumberStyles.Currency);
                TotalBonusAmount  = TotalMonthlySales * 0.02;

                SalesBonus             = PercentHoursWorked * TotalBonusAmount;
                SalesBonusTextBox.Text = SalesBonus.ToString("C2");
            }
            catch (Exception exception)
            {
                MessageBox.Show("Invalid Monthly Sales Entered", "Input Error");
                Debug.WriteLine(exception.Message);
                TotalMonthlySalesTextBox.Text = "";
                TotalMonthlySalesTextBox.Focus();
            }
        }