Penny candy was sold as a "change-maker" from jars and bins adjacent to the cash register (what is now termed the cash wrap area). Instead of three cents change, customers were thereby encouraged to spend their small change on candy.
In Hawaii, until the early '90s, penny candies were traditionally various kinds of dried and salted fruits or spiced seeds: plum/prune, pineapple, mango, pumpkin seed, etc.; imported from the Asian Pacific rim. This has been in decline due to children's taste evolving towards sweeter sugar-based snacks, and as chocolates that can withstand warmer climates have improved in taste.