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

Currently I'm doing it by getting the decimal values using:

let numbers = 5.33
let decimal = (numbers - rint(numbers)) * 100
let rounded = rint(numbers) + (5 * round(decimal / 5)) / 100

// This results in 5.35

I was wondering if there's a better method with fewer steps because sometimes numbers - rint(numbers) is giving me a weird result like:

let numbers = 12.12
let decimal = (numbers - rint(numbers)) * 100

// This results in 11.9999999999999

Answer 1

Turns out..it's really simple

let x: Float = 1.03 //or whatever value, you can also use the Double type
let y = round(x * 20) / 20

Answer 2

It's really better to stay away from floating-point for this kind of thing, but you can probably improve the accuracy a little with this:

import Foundation

func roundToFive(n: Double) -> Double {
  let f = floor(n)
  return f + round((n-f) * 20) / 20
}

roundToFive(12.12) // 12.1