code: function (index) {
        // Get the closest top fraction.
        var fraction = Math.ceil(index % 1 * this.options.fractions) / this.options.fractions;
        // Truncate decimal trying to avoid float precission issues.
        var p = Math.pow(10, this.options.scale);
        return Math.floor(index) + Math.floor(fraction * p) / p;
      }
docs: Round index to the configured opts.fractions.