I pay $70 for the city of Portland Arts tax. Where do I enter this so that it shows up as a "State and local tax" on OR-A (Oregon Itemized Deductions) line 5?

This will carry through from the federal return where it is also deductible. 

To enter it on your federal return:

1. Select Start/Revisit next to Local estimated taxes for 2021 in Federal > Deductions & Credits > Estimated taxes
2. Answer Yes to Did you pay local estimated taxes for 2021?
3. Use the pull-down menu underneath Additional Payments to select Portland Arts Tax, OR and enter your amount paid

Got it. Yes, this worked. Thanks for your help @RaifH!