I'm not sure if any of them have nice JSON interfaces yet, but there are certainly 3rd-party services where you can query geographically detailed information on

I'm not sure if any of them have nice JSON interfaces yet, but there are certainly 3rd-party services where you can query geographically detailed information on sales taxes, down to exactly which SKUs are taxed at which rates (e.g. what qualifies for a "grocery" exemption). Example: http://tax.cchgroup.com/sales-tax-data/default.htm?cookie_test=1 http://tax.cchgroup.com/sales-tax-data/default.htm?cookie_te...