generally no. They do sell stuff like that as well, but most is out in the open and you bag yourself. And then punch in the item codes or look them up at the self checkout. There's no real check, although sometimes they catch people cheating by reviewing video.
There's no extra tags involved, you just have to select what the produce is if it doesn't have a barcode.
There is indeed an opportunity to "cheat" by weighing something expensive but telling the machine it's something cheap like onions or potatoes.
But the machines can be monitored remotely from a security station, so there is a small chance you'd get caught. That keeps most people pretty honest.
I'm sure a few cheats do slip though, but the losses from this sort of thing are presumably much less than the savings from employing less checkout staff!
I've seen one location go from requiring an assistant to allowing full self-serve.
Not sure about the U.S. but I have the impression that there must be places which are similar in the U.S.