Probably, but it depends on the school and your kid's major. If the university charges by the credit, and AP credits allow your son or daughter to enroll in fewer credits, then yes, each AP credit saves you money on tuition. Be advised however that some schools charge by the semester, with students being allowed to enroll in however many credits they want (up to a certain limit). In that pricing system, AP credits may allow your kid to take a lighter schedule but they may or may not save you any money if they still take eight semesters to graduate.
My son attends a university that prices that way. He came in with 24 credits of AP and dual-enrollment credits. But he's a chemistry major who is also taking secondary education coursework. There's a bunch of sequencing in there -- he had to get through Calc III before he could enroll in some of his Chemistry courses, and those courses themselves run in sequences, and the education branch creates another sequence of its own. The end result is that he's still going to be there for four years to get all his required courses done -- he'll just graduate with more credits than he technically needs. If he were an English major, which is way less structured, he could have gotten deeper into his major earlier and probably shaved off a semester.
The way I described it may make it sound like that pricing strategy is a screwjob. It isn't. The idea behind charging students a flat per-semester tuition is to encourage them to take full loads (you're paying the same whether you take 12 credits or 15, so why not take 15?) which helps them get done on time. If your student body is primarily residential full-time students, as opposed to a bunch of part-timers, it makes a lot of sense. It just happens to take some of the shine off AP credit sometimes.