Groupon offers up to $3 cashback in card credit with qualifying purchases at Dunkin' Donuts, via the instructions below. (The statement credit takes a few days to appear in your account.) Deal ends April 19. To avail of this:
  1. "Claim" the deal on this page
  2. register your credit card for the claim
  3. visit your local Dunkin' Donuts and pay with your card to earn 100% cashback in credit on your first purchase (up to $3)
  4. thereafter, earn up to 10% back (again, up to $3) with each successive purchase through April 19