Loop Problem

[josh26757]

I am in college for programming, but my programming classes do not start until January. I am trying to work on C++ to get ready for my classes. I am currently in Personal Finance class and was intrigued by an interest calculator. I am not done the code because I need to add the compound interest section in the final loop. The problem I can't seem to fix is updating the minimum payment after each monthly payment. I also need to section off the part that chooses a set payment or a minimum payment. I just wanted to point out I am aware of this and know I need to fix it.

The problem: If I add payment=total*MinInterest(this is defined as .03 for 3&#37 then the loop gets stuck. I also used the math::ceil() for the wrong reason. I was trying to find a way to trim the double variables down to two decimal places(0.00) Can someone explain why I am having the loop problem and what I need to work on as far as code. I take all your advice very seriously and am anxious to learn. Here is the code.
BTW I am using DEV-C++

#include <cstdlib>
#include <iostream>
#include "math.h"
#define year 12
#define MinInterest .03
#define DaysInCycle 30

using namespace std;
// Displays Program Header
void menu()
{
   cout<<"@@@@@@@@@@@@@@@@@@@@\n"
       <<"@                  @\n"
       <<"@   Credit         @\n"
       <<"@    Card          @\n"
       <<"@     Payoff       @\n"
       <<"@      Calculater  @\n"
       <<"@                  @\n"
       <<"@@@@@@@@@@@@@@@@@@@@\n";
       
}  
//Gets Bill Total
double bill_total()
{
 double total;
 system("CLS");
 menu();
 cout<<"Please Enter The Total Amount:";
 cin>>total;
 total=ceil(total);
 return total;
}
// Gets APR
double APR()
{
  system("CLS");
  menu();
  double APR;
  cout<<"Please Enter APR:";
  cin>>APR;
  APR=ceil(APR);
  return APR;
}
//Gets User's Payment If PaymentSelection == 2
double GetPayment()
{
  double ammount;
  system("CLS");
  menu();
  cout<<"Please Enter Payment Ammount:";
  cin>>ammount;
  return ammount;
}
//Calculates Minimum Payment
double CalculateMinPayment(int total)
{
  return (total*MinInterest);
}
//User Selects Set Ammount Or Minimum Payment Style
double PaymentSelection(int total)
{
  int choice;
  do{
  system("CLS");
  menu();
  cout<<"1.Minimum Payment 2.Set Payment\n";
  cin>>choice;
  if(choice==1)
  return CalculateMinPayment(total);
  else if(choice==2)
  return GetPayment();
  }while(choice!=1||choice!=2);
}
//Finale Calculation
void calculate(double APR,double Payment,double Total)
{
  //initilize
  double TotalInterest=0,MonthlyInterest=0,Principal=0,AverageDailyBalance=0,TotalPaid=0;
  double month=1.0;
  
  //loop tell total is paid
  while(Total>0){
  //calculate monthly APR
  APR=ceil(APR);
  //calculate monthly interest
  MonthlyInterest=(APR/year)/100;
  //calculate Average Daily Balance
  AverageDailyBalance=Total/DaysInCycle;
  //Find Total Interest Paid
  TotalInterest=AverageDailyBalance*MonthlyInterest;
  //round total interest
  TotalInterest=ceil(TotalInterest);
  //Calculate principal paid
  Principal=(Payment-TotalInterest);
  //Calculate total for next month bill
  Total=(Total-Principal);
  //Keep track of total paid
  TotalPaid=TotalPaid+Payment;
  month++;}
  
  system("CLS");
  cout<<"It will take you "<<(month/12)<<" years to pay off the ammount.\n";
  cout<<"And it will cost you "<<TotalPaid<<"$"<<" total\n";
  
}
int main(int argc, char *argv[])
{
   menu();
   double total=bill_total();
   calculate(APR(),PaymentSelection(total),total);
   system("PAUSE");
   return EXIT_SUCCESS;
}