Change Calculator

#include <iostream>
#include <string>
#include <math.h>
using namespace std;

int main ()
{
    int numHundred, numTwenty, numTen, numFive, numOne, numQuarter, numTencents, numFivecents, numOnecent;
    double value;

    cout << "Insert a monetary value you would like to convert" << endl; //asks the user for a value
    cin >> value;
    while(value < 0){ //to always get a positive value
        cout << "Invalid value" << endl;
        cin >> value;
    }

    cout << "\nYour change is: " << endl; //heading
    cout << "Dollars \tNumber of Bills" << endl;

    if(value >= 100){ //if bigger than 100, say how many bills and subtract from the value
        numHundred = value / 100;
        cout << "$100 \t\t" << numHundred << endl;
        value = value - numHundred * 100;
    }
    if(value >= 20){ //if bigger than 20, say how many bills and subtract from the value
        numTwenty = value / 20;
        cout << "$20  \t\t" << numTwenty << endl;
        value = value - numTwenty * 20;
    }
    if(value >= 10){ //if bigger than 10, say how many bills and subtract from the value
        numTen = value / 10;
        cout << "$10  \t\t" << numTen << endl;
        value = value - numTen * 10;
    }
    if(value >= 5){ //if bigger than 5, say how many bills and subtract from the value
        numFive = value / 5;
        cout << "$5   \t\t" << numFive << endl;
        value = value - numFive * 5;
    }
    if(value >= 1){ //if bigger than 1, say how many bills and subtract from the value
        numOne = value / 1;
        cout << "$1   \t\t" << numOne << endl;
        value = value - numOne * 1;
    }
    if(value >= 0.25){ //if bigger than 0.25, say how many coins and subtract from the value
        numQuarter = value / 0.25;
        cout << "$0.25 \t\t" << numQuarter << endl;
        value = value - numQuarter * 0.25;
    }
    if(value >= 0.10){ //if bigger than 0.10, say how many coins and subtract from the value
        numTen = value / 0.10;
        cout << "$0.10 \t\t" << numTen << endl;
        value = value - numTen * 0.10;
    }
    if(value >= 0.05){ //if bigger than 0.05, say how many coins and subtract from the value
        numFivecents = value / 0.05;
        cout << "$0.05 \t\t" << numFivecents << endl;
        value = value - numFivecents * 0.05;
    }
    if(value >= 0.01){ //if bigger than 0.01, say how many coins and subtract from the value
        numOnecent = value / 0.01;
        cout << "$0.01 \t\t" << numOnecent << endl;
        value = value - numOnecent * 0.01;
    }

    return 0;
}