My experience:
I have 2 prior parking tickets, not in my name (rental vehicles). My impression was that these do not need to be mentioned since I'm fairly sure USCIS isn't looking for minor traffic violations. There are a lot of anal posters here who think they should be mentioned. They are right that the instructions do not say specifically that minor traffic tickets do not need to be mentioned (only that documentation for violations <$500 is not required), but there's a lot of info not specified by the instructions. My experience is that if you mention anything to USCIS, they will ask for documentation, so best be honest, and have the evidence on-hand, but best not provide any not-required information as it can only cause delays.
In any case, prior to submitting N400, I called USCIS national customer service and told the agent about my parking tickets. His answer, specifically, was 'minor traffic ticket don't count'. That was enough reassurance for me. I wrote down his agent number and the time/date of my call. I did not write down these tickets on my N400, but I did get copies of the tickets from the city (not court dispos since it was just parking tix) as well as evidence that I paid them.
At the interview, when the officer got to that question, he asked: were you ever arrested, received a citation or a ticket? Because he mentioned the ticket specifically, I answered yet, but that I did not put it down because I was previously told it doesn't count. He said that fine, did I have a copy of it, I said yes and provided him with the copy. He said it looked fine and moved on and I was approved. I don't know if he would have approved me if I did not have a copy available.