how to develop GST Calculation in java

import java.util.*;

class Gst{

 public static void main(String arg[]){

float amount;

float gstrate;

float gst;

  float total;

System.out.println("enter the amount for GST calculation");

Scanner n=new Scanner(System.in);

amount=n.nextInt();

System.out.println("enter the Gst rate for GST calculation");

Scanner gr=new Scanner(System.in);

gstrate=gr.nextInt();

System.out.println("enter amount = "+amount+"  Gst Rate =  "+gstrate+"%");

gst=(amount*gstrate)/100;

total=amount+gst;

System.out.println("GST calculation");

if(gstrate==5)

{

System.out.println("GST calculation in 5% ");

System.out.println("Total Gst "+gstrate+"% charge ="+gst );

System.out.println("Total Amount ="+total);

}else if(gstrate==12)

{

System.out.println("GST calculation in 12% ");

System.out.println("Total Gst "+gstrate+"% charge ="+gst );

System.out.println("Total Amount ="+total);

}else if(gstrate==18)

{

System.out.println("GST calculation in 18% ");

System.out.println("Total Gst "+gstrate+"% charge ="+gst );

System.out.println("Total Amount ="+total);

}else if(gstrate==28)

{

System.out.println("GST calculation in 28% ");

System.out.println("Total Gst "+gstrate+"% charge ="+gst );

System.out.println("Total Amount ="+total);

}

else{

System.out.println("as per indian rule gst calculate only 4 type 5%,12%,18%,28% ");

System.out.println(" you type GST RATE "+gstrate);

}

}

}