I hope you are having a great weekend so far! In regards to tax codes and bank rules, you can absolutely automate tax codes when you are creating a bank rule.
To assign an automatic Tax Code you will want to use the highlighted area down below:
As of right now, there is now "Dollar Amount" one can assign to a Bank Rule, but that would be an awesome idea for an upcoming feature! To give feedback for possible upcoming features of the program you can do so right in the product. You can find the steps in the link down below: