You are being asked for your state and local sales tax rate to calculate the sales tax deduction for Itemized Deductions.
You didn't indicate what state you lived in, so I can't give you a specific link to find your sales tax rate. Below are several suggestions for finding your sales tax rate:
1. You can look at a sales receipt (that you know was purchased in your county)
2. You can google sales tax rate for (your state)
3. Or you can click here to go to your state's Department of Revenue. You can search for the state sales tax rates once you are at your state's website.