Search code examples
javaroundingcurrency

Rounding to multiples of 5

I'd like make my program to be even more precise and to consider that there aren't coins for 1,2,7 values (only 5,10,20,50,100..), so there is a rule called rounding to five forints.

Example:

111,112  -> 110 
113,114  -> 115
116,117  -> 115
118,119  -> 120

My question is which function should I use in JAVA to reach my goal and get the right rounded value?

Solution

  • You could write it this way:

    int roundTo5(int value)
{
    return ((value + 2) / 5) * 5;
}

    This takes any forint value, adds 2 and divides by 5. This makes a "floor rounding" of integers and multiplies 5 again.

    0 → 2 → 0 → 0
1 → 3 → 0 → 0
2 → 4 → 0 → 0
3 → 5 → 1 → 5
4 → 6 → 1 → 5
5 → 7 → 1 → 5
6 → 8 → 1 → 5
7 → 9 → 1 → 5
8 → 10 → 2 → 10
9 → 11 → 2 → 10