Get shipping tax rate

Question

I have the following code to get the tax rate of a product

$store = Mage::app()->getStore();
$taxCalculation = Mage::getModel('tax/calculation');
$request = $taxCalculation->getRateRequest(null, null, null, $store);
$taxClassId = $product->getTaxClassId();
$percent = $taxCalculation->getRate($request->setProductClassId($taxClassId));

But I need the tax rate for the shipping costs for this product. Is there a way to get it?