Hi T.,
I have never worked in a child care facility, but I have had some experience with a few as a working mom.
On holidays, they were usually closed, just like school. But days like the day before Thanksgiving and after Christmas, they have always been open because working parents still have to work and still need someone to watch their children. I would assume the same goes for state/city run facilities. They have to be paid for days they are open, as long as parents need child care providers.
Check into contracts if you can. See what stipulations there are for optional closing for days that are not holidays. Your boss and the parents may have already made alternate arrangements for days that are not holidays.
I would try to check into this, as a concerned employee, that she will not be working alone, while caring for children, when she is required to have help for more than a few children. (child/caregiver ratio, I'm not sure what the ratio is) These could bring her more trouble than its worth to keep the money for herself!!