protected function getMinValue()
    {
        $minValue = $this->getFilter()->getMinValue();

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

        return $minValue;
    }