Round currency closest to five

Question

I\'d like to round my values to the closest of 5 cent for example:

5.31 -> 5.30
5.35 -> 5.35
5.33 -> 5.35
5.38 -> 5.40

Currentl

Answer 1

Depending on how you are storing your currency data, I would recommend using a dictionary or an array to look up the original cents value, and return a pre-computed result. There's no reason to do the calculations at all, since you know that 0 <= cents < 100.

If your currency is a string input, just chop off the last couple of digits and do a dictionary lookup.

round_cents = [ ... "12":"10", "13":"15", ... ]

If your currency is a floating point value, well, you have already discovered the joys of trying to do that. You should change it.

If your currency is a data type, or a fixed point integer, just get the cents part out and do an array lookup.

...
round_cents[12] = 10
round_cents[13] = 15
...

In either case, you would then do:

new_cents = round_cents[old_cents]

and be done with it.