C programming help - Adding Values together

So I have this code but I'm missing something and I can't quite seem to get it. The point of this is to prompt the user for a selection. They pick the food that they want to order, and it tells them it is added. When the user hits 0 the program ends by saying what the total is of all the items they chose. For some reason when I hit the end, it just states the total of the last item added. Any ideas on how to fix this so that the totals all add up?

#include<stdio.h>

#define SALES_TAX .06

int selection;
double total;
double amount;
int i;

double getPrice(int selection);


void printOptionName(int selection);


void printMenu();


double getPrice(int selection){

    if (selection == 1){
        amount = 5.99;
    } else if (selection == 2){
        amount = 6.99;
    } else if (selection == 3){
        amount = 7.99;
    } else if (selection == 4){
        amount = 10.50;
    } else if (selection == 5){
        amount = 3.50;
    }

}

void printOptionName(int selection){

    if (selection == 0){
        printf("\nYour total is: ");
    } else if (selection == 1){
        printf("\nAdded a Small Pizza\n\n");
    } else if (selection == 2){
        printf("\nAdded a Medium Pizza\n\n");
    } else if (selection == 3){
        printf("\nAdded a Large Pizza\n\n");
    } else if (selection == 4){
        printf("\nAdded an order of Wings\n\n");
    } else if (selection == 5){
        printf("\nAdded a Drink\n\n");
    } else
        printf("Not a valid selection. Please select one of the following options: \n");
}


void printMenu(){

printf("0. (Complete Order)\n");
printf("1. Small Pizza ****** 5.99\n");
printf("2. Medium Pizza ****** 6.99\n");
printf("3. Large Pizza ****** 7.99\n");
printf("4. Wings ****** 10.50\n");
printf("5. Drink ****** 3.50\n");
printf("Enter the Number of your selection: \n");

}

int main(){

    printMenu();
    scanf("%d", &selection);
    printOptionName(selection);
    getPrice(selection);

    while (selection != 0){
        printMenu();
        scanf("%d", &selection);
        printOptionName(selection);
        getPrice(selection);
    }

    for (i = 0; i <= selection; i++){
        total = total + amount;
    }

    printf("%lf\n", total);

    return 0;
}