Hotcakes is on a mission to provide the most flexible eCommerce platform possible that allows you to meet the needs 
of almost any eCommerce use case. That's why we made sure you have a way to implement your own or third-party tax 
calculation providers. This solution will help you implement any custom tax provider using the Visual Studio sample 
solution. It is almost the same as implementing a custom payment gateway for credit cards.

Documentation:  https://hotcakescommerce.zendesk.com/hc/en-us/articles/207999176-Tax-Provider-Extension-Point