I have never used one. I'm pretty cheap insofar as I don't buy many things, but when I do, I can afford them with cash in hand. I also try to be very self reliant and the penny dish, ever so slightly, is taking from others, so it doesn't appeal to me. It's like the jar of pork rinds on the counter. It's for someone else.
What has happened, several times, is that the cashier has used pennies from the dish, either to pay a few pennies of my bill, or to give me a few pennies of my change. I don't say anything about that, as it makes their job easier, I suppose.
I have never thrown pennies into the penny dish. I keep enough change in my pocket to pay exact change many times, or at least give the right number of cents to round to the closest quarter for my change. I empty my pants pocket change at night onto a shelf, and when the pile gets big enough, I put it into a jar. The jar is very useful for trips involving tolls and parking, or occasional trips to a store for something small. When I buy with change jar money, I almost feels like using birthday or Christmas money from childhood, so the process is enjoyable. I bought a $1.07 drive through burger with ten jar dimes and seven pennies the other day and was quite pleased with the process. Sometimes, it's the simple things that are the most fun.