Code Sales Program

[Ted Klingenberg]

I recently made this program (for learning, ignore the fake data). Is there a way I colud've made this program more efficiently? Btw, tax is supposedly 6% for the state.

   ////store-source.cpp calculates a////
  /////sample store's item's price/////
 ///////sale, code number and tax/////
///////Created by Ted - 09/02/2011///

#include <iostream>
#include <iomanip>
#include <string>

using std::cout;
using std::cin;
using std::endl;
using std::string;
using std::setprecision;
using std::fixed;
using std::getline;

int main(){
	/*Declare variables and constants*/
	bool n              = false; //n stands for Nike
	bool a              = false; //A for Adidas
	bool o              = false; //O for OP
	const double nike   = 15.99;
	const double adidas = 14.98;
	const double op     = 12.99;
	double shoe_size    =  1.50;
	int choice          =     0;
	char prompt_1       =   ' ';
	int item_code       =     0;
	string name         =   " ";
	double final_price  =  0.00;
	double tax          =  0.06;
	double priceToAdd   =  0.00;

	/*get user input*/
	cout << "What is the item's code number? " << endl;
	cin >> item_code;
		switch (item_code)
		{
			case 1:
				cout << "You have selected (1) Nike.\nIs this correct? (Y/N) " << endl;
				prompt_1 = islower(prompt_1);
				cin >> prompt_1;
				n = true;
				break;
			case 2:
				cout << "You have selected (2) Adidas.\nIs this correct? (Y/N) " << endl;
				prompt_1 = islower(prompt_1);
				cin >> prompt_1;
				a = true;
				break;
			case 3:
				cout << "You have selected (3) OP.\nIs this correct? (Y/N) " << endl;
				prompt_1 = islower(prompt_1);
				cin >> prompt_1;
				o = true;
				break;
			default:
				cout << "This code number does not exist in our system." << endl;
		}

		if(prompt_1 == 'n'){
		{
			cout << "Please try again.\nRestart this program. " << endl;
		}
		} //end if
		cout << "Now, what's your shoe size? " << endl;
		cin >> choice;
		switch(choice)
		{
		case 0:
			cout << "Invlid - well actually impossible...\n" << endl;
			break;
		case 1:
		case 2:
		case 3:
		case 4:
			final_price = shoe_size * 1;
			break;
		case 5:
		case 6:
		case 7:
		case 8:
			final_price = shoe_size * 2;
			break;
		default:
			final_price = shoe_size * 3;
		}

		//calculate final price
		if(nike == 15.99)
		{
			final_price = final_price + nike;
			priceToAdd = final_price * tax;
			final_price = priceToAdd + final_price;
		}
		else
			if(adidas == 14.98)
			{
			final_price = final_price + adidas;
			priceToAdd = final_price * tax;
			final_price = priceToAdd + final_price;
			}
			else
				if(op == 12.99)
				{
					final_price = final_price + op;
					priceToAdd = final_price * tax;
					final_price = priceToAdd + final_price;
				}

				//display answer
				cout << setprecision(2) << fixed;
				if(n == true)
				{
					cout << "The final price for your Nike shoes is: \n\t$" << final_price << endl;
				}
				else
					if(a == true)
					{
						cout << "The final price for your Nike shoes is: \n\t$" << final_price << endl;
					}
					else
						if(o == true)
						{
							cout << "The final price for your Nike shoes is: \n\t$" << final_price << endl;
						}
						else
							cout << "There was an error processing your request." << endl;
				cout << "Press the ENTER key to continue... " << endl;
				cin.ignore(10, '\n');
				cin.get();
	return 0;
} //end of main function 

This is an example output (for a successful run)

What is the item's code number?
3
You have selected (3) OP.
Is this correct? (Y/N)
y
Now, what's your shoe size?
6
The final price for your Nike shoes is:
        $20.13
Press the ENTER key to continue...