如何更新结帐页面中的运费？

Question

我想在发货信息流程后更新结帐页面上的运费。

$rates = Mage::getModel("checkout/session")->getQuote()->getShippingAddress()->getAllShippingRates();
        $shippingprice = 10;
        foreach($rates as $rate){
            $rate->setShippingAmount($shippingprice);
            $rate->setBaseShippingAmount($shippingprice);
            $rate->save();
        }