small console app to calculate change.

You would have to do continuous integer division for each set, subtracting after each division, ie:
double kleinGeld = 2000 - 111.12;
Console.WriteLine("Hundreds Rands: " + Math.Floor(kleinGeld / 100).ToString());
kleinGeld -= 100 * Math.Floor(kleinGeld / 100);
Console.WriteLine("Fifty Rands: " + Math.Floor(kleinGeld / 50).ToString());
kleinGeld -= 50 * Math.Floor(kleinGeld / 50);
.
.
.
Console.WriteLine("2 Cents: " + Math.Floor(kleinGeld / .02).ToString());
kleinGeld -= .02 * Math.Floor(kleinGeld / .02);
Console.WriteLine("1 Cents: " + Math.Floor(kleinGeld / .01).ToString());