Simple C programming question.

What am i doing wrong with switches here? The errors i get are compound statement missing (but i have it there) and function must return a value (How do i do this?) here is the code. Thanks in advance.

#include <stdio.h>
#include <conio.h>

int discount;
int quantity;
int price;
int gst;
int pst;
int total;
int disprice;

main()
{
printf("\nPress 1 ---> for a quantity of 1.");
printf("\nPress 2 ---> for a quantity of 2.");
printf("\nPress 3 ---> for a quantity of 3.");
printf("\nPress 4 ---> for a quantity of 4+.");
scanf("%d", &quantity);

switch (quantity)
{
      case 1:
         {
            printf("Enter the price:");
         scanf("%d", &price);
         gst=price+7%-price;
         pst=price+7%-price;
         total=price+gst+pst;
         printf("Quantity = %d", quantity);
         printf("GST = %d", gst);
         printf("PST = %d", pst);
         printf("Total = %d", total);
         break;
      }

   case 2:
         {
            printf("Enter the price:");
         scanf("%d", &price);
         discount=price+5%-price;
         disprice=price-discount;
         gst=disprice+7%-disprice;
         pst=disprice+7%-disprice;
         total=disprice+gst+pst;
         printf("Quantity = %d", quantity);
         printf("Discount = %d", discount);
         printf("GST = %d", gst);
         printf("PST = %d", pst);
         printf("Total = %d", total);
         break;
      }

   case 3:
         {
            printf("Enter the price:");
         scanf("%d", &price);
         discount=price+10%-price;
         disprice=price-discount;
         gst=disprice+7%-disprice;
         pst=disprice+7%-disprice;
         total=disprice+gst+pst;
         printf("Quantity = %d", quantity);
         printf("Discount = %d", discount);
         printf("GST = %d", gst);
         printf("PST = %d", pst);
         printf("Total = %d", total);
         break;
      }

   case 4:
         {
            printf("Enter the price:");
         scanf("%d", &price);
         discount=price+15%-price;
         disprice=price-discount;
         gst=disprice+7%-disprice;
         pst=disprice+7%-disprice;
         total=disprice+gst+pst;
         printf("Quantity = %d", quantity);
         printf("Discount = %d", discount);
         printf("GST = %d", gst);
         printf("PST = %d", pst);
         printf("Total = %d", total);
         break;
      }
}