public function getSubTotal()
    {
        $total = $this->UnitPrice * $this->Quantity;

        $this->extend("updateSubTotal", $total);

        return $total;
    }
public function getSubTotal()
    {
        $total = $this->UnitPrice * $this->Quantity;

        $this->extend("updateSubTotal", $total);

        return $total;
    }
public function getSubTotal ( ) { $ total = $ this -> UnitPrice * $ this -> Quantity ; $ this -> extend ( "updateSubTotal" , $ total ) ; return $ total ; }
Get the value of this item, minus any tax

@return float
Get the value of this item minus any tax