Extra fees are fees that are set on a per product basis through the Shopp Product Editor. A order handling fee applies once to an order and can be set through Shopp system –> Shipping settings. Currently these fees apply to all shipping options including paid and free shipping options.
In this tutorial, we’ll learn how to add a one-time additional shipping fee when products from a certain category are in the shopping cart for Shopp. This one-time additional shipping fee will be rolled into the existing shipping fee when any quantity of products from a certain category is added to the cart.
This will be done using the shopp_shipping_fees filter.
Here is an example of the filter: