source/Core/Price.php
public function subtractPercent($dValue)
    {
        $dPrice = $this->getPrice();
        $this->setPrice($dPrice - self::percent($dPrice, $dValue));
    }
public function subtractPercent($dValue)
    {
        $dPrice = $this->getPrice();
        $this->setPrice($dPrice - self::percent($dPrice, $dValue));
    }
public function subtractPercent ( $ dValue ) { $ dPrice = $ this -> getPrice ( ) ; $ this -> setPrice ( $ dPrice - self :: percent ( $ dPrice , $ dValue ) ) ; }
Subtracts given percent from price depending  on price entering mode,
and recalculates price

@param double $dValue percent to subtract from price
Subtracts given percent from price depending on price entering mode and recalculates price