Currently I don't see a way to have a quiz activity complete when all attempts are used. One can set completion based on a passing grade, but I don't see how a failing grade can be handled well because of multiple attempts. You may not mark the activity as complete on view or on any grade because that might be the first attempt of three, for example.
Is there something I'm missing? If not, I'll submit a patch to add a completion condition of "all attempts used" or something.
Edit - thinking about it more, what we really want, I think, is to consider it complete if they either pass or fail the quiz. Passing is supported - that's just getting a passing grade. Failing would mean getting a failing grade on all allowed attempts. Since the OR of conditions isn't quite supported, though it's partially coded, I'm not sure how to proceed.
I'm a little suprised - I would have thought others would have wanted to know when a student pased or failed, but I've not found any discussion in my searches. We can't be the only institution that wants to tracks when tests are passed and failed while allowing more than one attempt, can we? Am I missing something?