You cannot offer incentives of any kind for a review.
Shopper Approved is a Google Review Partner, and NOT incentivizing for reviews is their #1 rule. This is stated in Google's Fair Moderation Policies when collecting reviews:
"Merchants are not allowed to offer their customers financial incentives to write reviews of any kind."
If we find that any of our clients are incentivizing we have to submit those reviews to Google for removal as you can see stated in the above link.
See here for more information directly from the FTC: https://www.ftc.gov/business-guidance/resources/soliciting-paying-online-reviews-guide-marketers
Please note that you can, however, incentivize for video reviews as these are collected after the seller and product review.