round to nearest step

1function round(number, increment, offset) {
2    return Math.ceil((number - offset) / increment ) * increment + offset;
3}
4round(51,  20, 10) // 70
5round(70,  20, 10) // 70
6round(99,  20, 10) // 110
7round(100, 20, 10) // 110
8