Rounding to nearest 100

Question

First number needs to be rounded to nearest second number. There are many ways of doing this, but whats the best and shortest algorithm? Anyone up for a challenge :-)

Answer 1

I know it's late in the game, but here's something I generally set up when I'm dealing with having to round things up to the nearest nTh:

Number.prototype.roundTo = function(nTo) {
    nTo = nTo || 10;
    return Math.round(this * (1 / nTo) ) * nTo;
}
console.log("roundto ", (925.50).roundTo(100));

Number.prototype.ceilTo = function(nTo) {
    nTo = nTo || 10;
    return Math.ceil(this * (1 / nTo) ) * nTo;
}
console.log("ceilTo ", (925.50).ceilTo(100));

Number.prototype.floorTo = function(nTo) {
    nTo = nTo || 10;
    return Math.floor(this * (1 / nTo) ) * nTo;
}
console.log("floorTo ", (925.50).floorTo(100));

I find myself using Number.ceilTo(..) because I'm working with Canvas and trying to get out to determine how far out to scale.