Comment Re:Wrong focus (Score 2) 297
You forgot the other issue. Different products may be subject to different tax levels. For example, in one state, tea has sales tax. In another, tea has no sales tax. So you have to hold in your database not only all the varying rates, but the lists of what items are subject to what tax levels, and keep that database updated on probably a daily basis.
And yes, my tea vendor says Massachusetts has a tax on tea.