In my experience, recitation grades are a good way of rewarding students who show up and show willing to put in the work, even if they're struggling with the material. They are the discretion that teachers are supposed to have in interpreting performance.
Many of your students are already probably stressed, so it's good to make recitation a safer space for the "dumb questions" that they need to ask but may feel shy about. Don't add quizzes (and stress) for the sake of justifying the 5%. Instead, let the 5% be extremely easy to earn by just being there---basically, "Did you generally show up and try to engage with the material?"
How formal you need to be in your policy depends on your university policy. When I was a TA, we used it informally in the end of semester grading meeting. First we would compute grades as though the recitation grade was not part of the formula. Then, for students just below the boundary of a higher letter-grade the professor would ask the TA, "How hard did this student work?" If the TA said they were showing up consistently and putting in the effort, that was "a good recitation grade" and the student got rounded up. If the TA said the student didn't bother showing up or was otherwise problematic, that was "a bad recitation grade" and the student didn't get the bonus and stayed at the lower grade. I liked this system very much because nobody was ever hurt by the recitation grade, but if they needed it, they could be given a small bonus for working hard.
If the university has a computerized computation where you have to give a precise formula, you can't be so informal. You can accomplish a similar effect, however, with something like: "5% if you attend at least 2/3 of recitations, minus 1% per skipped recitation below that."