NicholasW believes (offhand) that "used to" is never pronounced like the normal verb 'used' with a /zd/.

I agree, "I used to get up late" and "I used two cans of paint" are pronounced differently, the former "used" ending with a /t/, the latter wit the /zd/ as NicholasW states.

Listening to myself, for the negative I say "used not to get up till 12" or "used to not get up till 12", both still with the /t/ ending. I'm not sure about the grammatical validity of the second but I use it.

Rod