Using your plugin, I had a problem with my taxation, it was always coming up zero for any Customer who hits your One Page cart page. The plugin creates BLANK, null records in the Address table and associates them with the Customer. Any subsequent carts will refuse to display tax, not certain what else might be the result. I've not been able to use the plugin for our store because of this bug. I tried to document this with your staff and they essentially refused to do anything about it unless I gave them admin access to my store. It's not necessary to gain access to my store, you can test the issue yourself. http://stackoverflow.com/questions/31633500/nopcommerce-3-6-tax-by-country-state-zip-always-results-in-zero-tax