protected function getMaxValue()
    {
        $maxValue = $this->getFilter()->getMaxValue() + 1;

        if ($this->isManualCalculation() && ($this->getStepValue() > 0)) {
            $stepValue = $this->getStepValue();
            $maxValue  = ceil($maxValue / $stepValue) * $stepValue;
        }

        return $maxValue;
    }