The University of Phoenix on Thursday announced an immediate tuition freeze for all new and currently enrolled students. Tuition rates will be locked in for students as they work toward degrees, university officials said, as long as they meet eligibility requirements and stay enrolled. The university said the freeze was an effort to keep tuition levels affordable at Phoenix, which is the largest for-profit institution. Tuition rates vary at the university, but some bachelor's degree programs are $420 per credit.