Are you allowed to incentivize app store reviews? If so to what length?

Read through the developer guidelines which state: (3.10: Developers who attempt to manipulate or cheat the user reviews or chart ranking in the App Store with fake or paid reviews, or any other inappropriate methods will be removed from the iOS Developer Program.) However this seems vague and I was hoping for a more detailed understanding of what is permitted and what isn't. Are there any types of incentivizing users that are permitted? What is the extent, and will an app get shut down for giving users any in-app motive for providing a review. Thank you.