Setting Up County Sales Taxes
From Opentaps Wiki
In many states of the United States, there is a different sales tax rate collected for each county. Some tax authorities, such as the State of California's Board of Equalization, requires that you report, the base tax for the state plus a differing percentage for each county. Others, like the state of New York's Department of Taxation and Finance, simply want you to report the sales in each county at a different rate. In all cases that we know of, if a customer exempt from state sales tax, they would be exempt from county sales tax as well.
opentaps allows you to charge different sales tax rates for each county of residence by using the zip code of the shipping address to determine the county. To help you set up the different sales tax rates for each county, the opentaps data import application has two entities, DataImportUSZipCodes and DataImportCountyTaxRate, for importing the mapping of five digit zip codes to counties and the tax rate in each county. Once you have loaded the data there, run importUsTaxRates for each of your stores.
How you should set up a county sales tax rates depends on the way it should be reported. If your state wants to see a state-level tax, plus a county level attacks, then set up a state-level tax, and then use DataImportUSZipCodes to set up the additional tax in your county. If you are state wants to see a county level rate that includes both state and county taxes, then do not set up a separate rate for the state only. Set up the entire rate for each county.
Once your orders have been shipped and invoiced, you can use the Sales Tax Statement report in opentaps financials to see a breakdown of your sales tax by state and county.