A retail company must file a monthly sales tax report listing the total sales for the month and the amount of state and county sales tax collected [on hold]

The state sales tax rate is 4% and the county sales tax rate is 2%. Create a GUI application that allows the user to enter the total sales for the month into a text field. from this figure, the application should calculate and display the following:

1. the amount of county sales tax.
2. the amount of state sales tax.
3. the total sales tax(county plus state).

In the applications, code represent the county tax rate (0.02) and the state tax rate by (0.04) as named constants.

Here is my code:

import javax.swing.*;
import java.awt.event.*;
import java.text.DecimalFormat;

public class SalesTax extends JFrame
{
    private JPanel panel;
    private JTextField totalSales;
    private JButton calcButton;

    private final double COUNTRY_RATE = 0.02;
    private final double STATE_RATE = 0.04;

    private final int WINDOW_WIDTH = 360;
    private final int WINDOW_HEIGHT = 100;

    public SalesTax()
    {
        super("Monthly Sales Tax Reporter");

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        buildPanel();

        add(panel);

        setSize(WINDOW_WIDTH, WINDOW_HEIGHT);
        setVisible(true);
    }

    private void buildPanel()
    {
        totalSalesMsg = new JLabel("Enter the total sales:");
        totalSales = new JTextField(10);

        calcButton = new JButton("Calculate Sales Tax");

        calcButton.addActionListener(new CalcButtonListener());

        panel = new JPanel();

        panel.add(totalSalesMsg);
        panel.add(totalSales);
        panel.add(calcButton);

    }
    private class CalcButtonListener implements ActionListener
    {
        public void actionPerformed(ActionEvent e)
        {
            double totalSalesAmount,
                countyTaxAmount,
                stateTaxAmount,
                totalTaxAmount;

            DecimalFormat dollar = new DecimalFormat("#,##0.00");

            totalSalesAmount = Double.ParseDouble(totalSales.getText());

            countyTaxAmount = totalSalesAmount * COUNTRY_RATE;

            stateTaxAmount = totalSalesAmount * STATE_RATE;

            totalSalesAmount = countyTaxAmount + stateTaxAmount;

            JOptionPane.showMessageDialog(null, "County Sales Tax: $"
                                                + dollar.format(countyTaxAmount)
                                                + "\nState Sales Tax: $"
                                                + dollar.format(stateTaxAmount)
                                                + "\nTotal Sales Tax:"
                                                + dollar.format(totalTaxAmount));
        }
    }

    public static void main(String[] args)
    {
        SalesTax stw = new SalesTax();
    }
}

this is what I got.

there is only 3 errors but I don't understand the problem with them.