I have a website in Magento 1.9 in which I have already configured a tax class for shipping rate from admin side. I want to change the tax rate for shipping if my cart contains some specific type of products and recalculate the total after the shipping tax class update. Is there any event for this or I need to override any core files?
Instade of changeing core files, you can used magento observer event. Some of the event which you can used are as follow.