This is going to sound like I've never been in public before probably, but I've never charged anything to my room (that's a lie. Once when I was out of town for work, all my expenses were charged to my room from the two in house restaurants and the actual stay, and I gave my card upon check in as requested, then they charged MY account instead of the business account and several scheduled bills bounced, so that was a fiasco).
So when I check in, do I say, please charge the gratuity to the room, or will they bring me a bill at the end and I say it then? I've also never been on the dining plan.