Function Troubles

#include<iostream>
#include<iomanip>
#include<Windows.h>
#include<string>

using namespace std;

double taxrateCalculator(double subtotal, double taxRate);
double tiprateCalculator(double costofmeal, double tipRate, int tipSelect);

int main()
{
    double walletcontents = 60, taxRate = 10 / 100, costofmeal, subtotal, bullets, remainder, mealTotal;
    int mealselect, storydecision1, storydecision2;
    string name, location;
    int tipSelect;

    cout << "Flavor Text...";
    cout << endl;
    cout << "Flavor Text...";
    cout << endl;
    system("pause");
    system("cls");
    cout << "Name Query?" << endl;
    cin >> name;
    cout << "Flavor Text..." << name << " Flavor Text....";
    cout << endl;
    system("pause");
    system("cls");
    cout << "Location Question?";
    cin >> location;
    cout << endl << "Flavor Text...";
    system("pause");
    system("cls");
    cout << "                   Menu Prototype                ";
    cout << endl << endl;
    cout << "Option 1.                      $35.00" << endl;
    cout << "Option 2.                      $45.00" << endl;
    cin >> mealselect;

    if (mealselect = 1)
    {
        subtotal = 35;
        costofmeal = 35;
        cout << "Response";
        system("pause");
        system("cls");
    }

    else if (mealselect = 2)
    {
        subtotal = 45;
        costofmeal = 45;
        cout << "Response";
        system("pause");
        system("cls");
    }

    cout << "Tip menu!";
    cout << endl << "1. 20%";
    cout << endl << "2. 15%";
    cout << endl << "3. 10%";
    cout << endl << "4. 5%";
    cin >> tipSelect;
    system("pause");
    system("cls");



    double totalTax = taxrateCalculator(subtotal, taxRate);
    double totalTip = tiprateCalculator(costofmeal, tipRate, tipSelect);

    cout << "Story Response. Bullet Query." << endl;
    cout << "Your meal was  $" << costofmeal << endl;
    cout << "Your total tax is $" << totalTax << "      " << endl;
    cout << "";


    system("pause");

}

double taxrateCalculator(double subtotal, double taxRate)
{
    taxRate = subtotal * 10 / 100;
    return taxRate;
}

double tiprateCalculator(double costofmeal, double tipRate, int tipSelect)
{
    double tip;
    while (tipSelect = 1)
    {
        tip = costofmeal * (20 / 100);
        return tip;
    }

    while (tipSelect = 2)
    {
        tip = costofmeal * (15 / 100);
        return tip;
    }

    while (tipSelect = 3)
    {
        tip = costofmeal * (10 / 100);
        return tip;
    }

    while (tipSelect = 4)
    {
        tip = costofmeal * (5 / 100);
        return tip;
    }

    tipRate = tip * 1;
    return tipRate;
}