A quick instant answer triggered by "sales tax for [insert state name here]". Ideally, this could be used both with the codes (PA for Pennsylvania) and the actual state name. Proposed by @AJDev, written up on duck.co by me.
There is no real source involved...@AJDev and I personally pulled the sales taxes per state off the web (Wikipedia) and put it in a spreadsheet for now. We'll be working on this.