Model/Api/Data/ShippingOptions.php
public function addAmountToShippingOptions($amount){
        foreach ($this->getShippingOptions() as $option) {
            $option->setCost($option->getCost() + $amount);
        }

        return $this;
    }
public function addAmountToShippingOptions($amount){
        foreach ($this->getShippingOptions() as $option) {
            $option->setCost($option->getCost() + $amount);
        }

        return $this;
    }
public function addAmountToShippingOptions ( $ amount ) { foreach ( $ this -> getShippingOptions ( ) as $ option ) { $ option -> setCost ( $ option -> getCost ( ) + $ amount ) ; } return $ this ; }
Add amount to shipping options.

@api
@param int $amount

@return $this
Add amount to shipping options .