Basic cash system in C++ - c++

Question

In the below code, I've got some bugs and I don't know why it doesn't work.
I used a fmod to do the decimals but I got some bugs in the part where it gives you the 0.10 and 0.05 $ and most of the time I never get the good amount that I'm supposed to give back if there is.
#include<iostream>
#include <cmath>
using namespace std;
int main()
{
int iAmount_due = { 0 };
int iGiven_money = { 0 };
int iMoney_back;
iMoney_back = iGiven_money - iAmount_due;
cout << "Enter the amount due please: " << endl;
cin >> iAmount_due;
cout << "Enter the amount given please: " << endl;
cin >> iGiven_money;
if (iGiven_money >= iAmount_due) {
iMoney_back = iGiven_money - iAmount_due;
cout << "We will give you : " << iMoney_back << " $ back" << endl;
}
else {
cout << "No money back" << endl;
}
if (iMoney_back >= 100) {
cout << "You will receive: " << iMoney_back % 100 << " x 100$" << endl;
}
else {
cout << "No 100$ bill" << endl;
}
if (iMoney_back >= 50) {
cout << "You will receive: " << iMoney_back % 50 << " x 50$" << endl;
}
else {
cout << "No 50$ bill" << endl;
}
if (iMoney_back >= 20) {
cout << "You will receive: " << iMoney_back % 20 << " x 20$" << endl;
}
else {
cout << "No 20$ bill" << endl;
}
if (iMoney_back >= 10) {
cout << "You will receive: " << iMoney_back % 10 << " x 10$" << endl;
}
else {
cout << "No 10$ bill" << endl;
}
if (iMoney_back >= 5) {
cout << "You will receive: " << iMoney_back % 5 << " x 5$" << endl;
}
else {
cout << "No 5$ bill" << endl;
}
if (iMoney_back >= 0.25) {
cout << "You will receive: " << fmod (iMoney_back, 0.25) << " x 0.25$ " << endl;
}
else {
cout << "No 0.25$ " << endl;
}
if (iMoney_back >= 0.10) {
cout << "You will receive: " << fmod (iMoney_back, 0.10) << " x 0.10$ " << endl;
}
else {
cout << "No 0.10$ " << endl;
}
if (iMoney_back >= 0.05) {
cout << "You will receive: " << fmod (iMoney_back, 0.05) << " x 0.05$ " << endl;
}
else {
cout << "No 0.05$ " << endl;
}
return 0;
}

Answer 1

int holds only integer values. 0.05 is not an integer value. You might be tempted to use double values instead that probably work for your simple problem; however, they generally have rounding errors which is something you really do not want to have with currency values.
The better solution will be to still use integers. You would need to define 1 as the smallest possible unit (e.g. 1 cent), meaning that all your values will be in cent. You would need to write extra code to be able to enter and display values as dollars instead of cents.