I would like to apply a tax rule for any customer who is shipping to New Jersey. I would ideally like to update the cost and tax amount via an AJAX call from the onepage checkout. I have a customised OnepageController to manage this currently, so the shipping amount is updated via AJAX.
I have entered a tax zone & rate for every US state, set to 0% except for New Jersey. I have then created the associated Tax Rule, one for every state except NJ, then one for NJ only. Now it will apply NJ tax to every customer no matter what, even if I change the shipping state to one I know does not have an associated tax rule.
I have a customised checkout that starts with the shipping address (after guest checkout / login). I don't understand why Magento is not applying the tax rules I have defined. It seems simple enough in principle.
I've looked at using TaxJar, and it has added a bunch of NJ tax rules. Unfortunately it also always applies the NJ tax no matter where I put the shipping address.
I've checked a lot of tutorials and posts and none of them helped. I've gone over all the admin settings many times and they are fine and how they should be (I think).
Any help to get this working would be much appreciated.