Do I need to add total sales tax rate to my return?

No, you don't have to enter any sales tax rates on your return.   If you're itemizing, you get to choose between deducting your state and local income taxes or your state and local sales taxes. You cannot claim both, and you can't claim either one if you're taking the standard deduction.  

For most people who itemize, the state and local income tax deduction gives them a bigger tax break.  However, the sales tax deduction may be more advantageous for taxpayers who:

• Are residents of Alaska, Florida, Nevada, South Dakota, Texas, Washington, or Wyoming
• Made a major purchase and therefore paid a lot of sales tax
• Made frequent or substantial purchases in a state with high sales taxes

If you take the standard deduction (most people do) - you do not deduct either and can skip this section.