HTMLPurifier_UnitConverter::round PHP Method

    private function round($n, $sigfigs)
    {
        $new_log = (int) floor(log(abs($n), 10));
        // Number of digits left of decimal - 1
        $rp = $sigfigs - $new_log - 1;
        // Number of decimal places needed
        $neg = $n < 0 ? '-' : '';
        // Negative sign
        if ($this->bcmath) {
            if ($rp >= 0) {
                $n = bcadd($n, $neg . '0.' . str_repeat('0', $rp) . '5', $rp + 1);
                $n = bcdiv($n, '1', $rp);
            } else {
                // This algorithm partially depends on the standardized
                // form of numbers that comes out of bcmath.
                $n = bcadd($n, $neg . '5' . str_repeat('0', $new_log - $sigfigs), 0);
                $n = substr($n, 0, $sigfigs + strlen($neg)) . str_repeat('0', $new_log - $sigfigs + 1);
            }
            return $n;
        } else {
            return $this->scale(round($n, $sigfigs - $new_log - 1), $rp + 1);
        }
    }