http://www.exactor.com/about-us/
Ugly and cumbersome as it seems, the writing is on the wall: sooner or later we’re going to have to collect taxes for other states and/or more granular jurisdictions in the state(s) where you have nexus (physical presence). To address this increasingly complex requirement we have developed an integration with the tax service Exactor.
The Exactor Module allows CMS to communicate with the Exactor web service API to obtain accurate taxing for all states you have nexus in (and suppress tax requests for non-nexus states). If your website is running on CommerceV3 or Magento, for example, they also support Exactor integration. Thus you can be sure that the taxing on your site is exactly the same as in CMS (solving both tax configuration and rounding issues commonly seen otherwise).
Not only can Exactor provide updated, accurate, and detailed tax for any address in the U.S., they can also, as a service, provide tax compliance reporting (filing your monthly/quarterly sales tax with the appropriate jurisdictions).
The convenience of not having to update tax tables in CMS alone is attractive enough, and add the peace of mind of knowing your taxes are accurate and that you’re protected from a sales tax audit, well, there ya go. The Exactor service/Module represents a pretty clear return on investment.