Program using C to calculate Electricity Bill with if-else condition

Conditions      

                <=100 Rs.4/units

                 > 100 and <=300 Rs.4.50/units

                 >300 and <=500 Rs.4.75/units

                 >500 Rs.5/units

Program

#include<stdio.h>

#include<conio.h>

void main ()

{

  int unit, tot;

  clrscr ();

  printf("Enter Total Units:");

  scanf ("%d", &unit);

   if (unit<=100)

     {

      tot=unit*4;

     }

   else if (unit>100 && unit<=300)

     {

      tot=unit*4.5;

     }

    else if (unit >300 && unit<=500)

     {

      tot=unit*4.75;

     }

   else

     {

      tot=unit*5;

     } 

    printf("Total Amount = %d", tot);

  getch ();

}