You will only get cashback at the register if the underlying card enrolled in Apple Pay is a debit card. Apple Pay transactions will behave exactly like transactions using the physical card.Since it seems like Apple Pay transactions are debit transactions (since Apple Pay requires a participating bank), I wonder if it will be possible to get cash back when using Apple Pay to make a purchase? Example, my last trip to Walgreens was to buy a pack of gum so I could get $20 cash.
Conversely, if the underlying card is a credit card, you will get all its benefits too (points/miles/rewards, purchase protection, and whatever other features the card has).