If options.convert is true then it would be helpful if number.precision would round the value to the specified precision instead of rejecting it. Similar to how string converts to lower/upper case.

Example conversion:

// in number._base
if (options.convert && 'precision' in this._flags) {
  var precision = Math.pow(10, this._flags.precision);
  value = Math.round(value * precision) / precision;
}