My clinical program (phd) is at a major state university. We do not have to pay any fees while on internship.
The only exception to this is if you still need to defend your dissertation, then you have to be registered for a certain number of credits during the semester in which you defend. (this would typically be covered by a TA/RA but since you give up these positions to go on internship, it would come out of pocket or fin aid).