How are you using Zip Code as a means of calculating county discretionary tax, when some zip codes split counties? For example 32696 is a Williston (city) zip code, 89% of the zip code resides in Levy county which has a 1% discretionary tax. The other 11% reside in Alachua county which has a .25% discretionary tax. So, my question is how are zip codes used to calculate county sales tax when they are not county specific???