I need to change a rate in SalesTaxII.
There are a number of different ways achieve this depending on your requirements.
Use the Customer or Product exemption tables to exclude specific jurisdictions so that you achieve the desired rate.
Create a special rate record for a product using Entity Code. This code must be different from any assigned by Avalara. It is the user’s responsibility to maintain this special rate.
Use the 'Other' rate available on every tax record to specify a special rate.