I used a Zip Code book, the NYS Communites PUB 717, made a word document by county, then copied and pasted the zips into shop site by sales tax rate. However, NYS wants the tax charged by the county to which the item is delivered...it's a pain. There are a handful of zips that are duo counties so I use the address look up on the NYS's web site to verify the county for these zips. The look-up is located here:
http://www7.nystax.gov/STLR/stlrHome
Some zips were entered with 3, 4 and 5 digits of the zip depending on the zip code and county.