Effective July 1, 2008, Washington changes from an "origin" based sales tax--one rate for my location--to a "destination" based tax, where I have to charge the customer's local city/county rate.
While you have the Zip based sales tax, it's meant for less fragmented data. It would greatly help if you added an import or lookup function, so I can pull in a CSV of Zip/name/rate to set my levels. And of course, values can change quarterly, which would be nice to handle with a scheduled rate change, but I can live with it being off a day or two. I'm using ShopSite Pro through Pair.
I don't suppose either the ecommerce community or a helpful government agency is considering a nationwide tax rate server? A great feature would be to indicate in ShopSite which states I collect tax for, then have it pull the rate in for applicable transactions. Much more intelligent (and accurate) than our current setup: millions of shopping carts and accounting software installations being individually updated.
Apparently WA did this to be consistent with the Streamlined Sales and Use Tax Agreement (SSUTA) of which more than 20 states are participating. More background on all this at http://destinationtax.dor.wa.gov
Cheers,
Ann