Fresh install v1.38a
I setup the Priority Handling Mod and I noticed something that may help you out - the mod will still calculate tax on on the priority handling fee when you are shipping out of state if the primary/default address for the user is a local address.

This has only happened on my test account so far since I have multiple addresses setup to test shipping, tax, and discounts are calculating properly. If a customer in my state of FL, however, wants to ship their product out of state, the customer will still be charged tax on the handling fee when they should not - unless they designate the ship to address as the primary (or default) address for the account.

Would be nice if there was a change for the code to modify how tax is calculated for the handling fee based on ship to address, but maybe I'm the only one with the problem?

Thanks