There is commercial software that 'does this' and 3-4 disagree on commonaddresses tax rates.   It is pretty easy to look up and lock in one or 3 or even 20 discrete locations but to do so with every location is nuts even within Colorado alone where there are over 3000 taxing entities.   Each of which can have their own rate own exemptions from what is taxed and change the rates whenever they want.


And tax districts don't break on zip +4