FWIW, I think 10 cents is probably sufficient. We have a 10 cent deposit here in Oregon. As a result, on the night before trash day in our neighborhood there is always a lady going through the recycling bins to pull out the cans and bottles with deposits. Growing up in Los Angeles, where they also have a deposit, it was common to see homeless people pushing trains of shopping carts down major thoroughfares filled with cans and bottles.