Sweet dayjs rounding function

round.js

// from https://github.com/iamkun/dayjs/issues/1619#issuecomment-1185714859

const round: PluginFunc = (option, dayjsClass) => {
  dayjsClass.prototype.round = function (amount, unit) {
    const mod = this.get(unit as UnitType) % amount;

    if(mod < amount / 2) {
      return this.subtract(mod, unit).startOf(unit);
    }

    return this.add(amount - mod, unit).startOf(unit);
  };
};