roundToMultipleOf

roundToMultipleOf.js

function roundToMultipleOf(multipleOf) {
  const factor = 1 / multipleOf;
  return num => Math.round(num * factor) / factor;
}

/**
 * EXAMPLE
 * Rounding to the closest multiple of five
 */
const roundToMultipleOfFive = roundToMultipleOf(5);

roundToMultipleOfFive(-32.31) // => -30
roundToMultipleOfFive(12.10)  // => 10
roundToMultipleOfFive(26.29)  // => 25
roundToMultipleOfFive(47.431) // => 45
roundToMultipleOfFive(62.111) // => 60