Do you have any questions?

Do you have any questions? Can you think of anything else you'd like to add?

Don't say "no," or that everything has been thoroughly discussed.

By saying you don't have any questions, the interviewer also may assume you're not interested in the job.
Have some intelligent questions ready that show you're knowledgeable about the company and the opening. This presumes that you've done your homework.

Thanks to Payal Sharma