A new $4.99 off one FandangoNow rental promo code showed up on my roku sleep screen. Sponsored by Microsoft, Microsoft Edge (had the new browser logo).
It says on the roku that its $4.99 off purchase, but its $4.99 off a rental in the T&C's in the email.
Rental promo code expires 7/30 (note it says 7/31 on your VIP Rewards page, but you usually have to use it by the day before by midnight Pacific time)
See attached picture of sleep screen ad, there also may be a vertical ad on the home screen or sleep screen too.