LocalLedger
LocalLedger keeps the bookkeeping records of a small business: the statements you upload, the transactions read from them, and a record of every action taken.
In LocalLedger's own words, from their site. TaxAndTips does not verify what a sponsor sells.
What sponsorship pays for
LocalLedger helps cover the cost of importing and checking tax rates from 20,189 taxing jurisdictions, so the calculator stays free to use. It buys no influence over a rate, which comes from the taxing authority's own publication and nowhere else.
Most of those jurisdictions are local — cities, counties, transit authorities and special districts — which is why what you pay at the till follows the street you are standing on. More on where that money goes.