Testing a Void method in Junit

Question

I'm new to JUnit and we got a simple Insurance program that we refactored and broke into some methods in order to test them using JUnit. But I have no idea how I should go about testing a void method like this:

private static void belowAge() {
        basicInsurance += surcharge;
        System.out.println("Additional surcharge " + surcharge);

        System.out.print("\nHow many accidents did you have? ");
        int accidents = scan2.nextInt();

        switch (accidents) {
        case 0:
            System.out.println("No surcharge");
            System.out.println("Total amount to pay: " + basicInsurance);
            break;
        case 1:
            System.out.println(
                    "Additional surcharge for accident: " + 50 
+ " \ntotal amount to pay: " + (basicInsurance + 50)); // Pay 650
            break;
        case 2:
            System.out.println(
                    "Additional surcharge for accident: " + 125
+ " \ntotal amount to pay: " + (basicInsurance + 125)); // Pay 725
            break;
        case 3:
            System.out.println(
                    "Additional surcharge for accident: " + 225 
+ " \ntotal amount to pay: " + (basicInsurance + 225)); // Pay 825
            break;
        case 4:
            System.out.println(
                    "Additional surcharge for accident: " + 375 
+ " \ntotal amount to pay: " + (basicInsurance + 375)); // 975
            break;
        case 5:
            System.out.println(
                    "Additional surcharge for accident: " + 575 
+ " \ntotal amount to pay: " + (basicInsurance + 575)); // 1175
            break;
        }