Start with the most generic rule and then specify the exceptions.
If the group is Sales Tax, for example, create one tax record for each state served (and where sales tax is charged) and specify the rate for that tax (skipping the Product and Use fields).
Next, specify the Exceptions to the general rule created. For example, if there is a different rate in a specific county, create a record for that county and specify a different rate.
If there are different rates for that tax in the same geographical region, based on the product sold, or the use of the product, specify multiple rates for each record and the product/use combination and rate associated with this combination.