Don't mess with the penny. There's been a movement around for years to "abolish the penny," as a unit of currency. One Dunkin' Donuts shop decided to take matters into its own hands (not as anything against the penny, but for the sake of "efficiency,") and put up a sign saying they'd just start rounding change
to the nearest nickel instead (unless you complained...):
Apparently, that lasted all of about a day, and due to "customer feedback," the shop has removed the sign
and will go back to giving (and taking) every penny. However, Dunkin Donuts corporate bosses have noted that franchises are free to do whatever they like, so if they want to ban the penny, they're free to do so (assuming local laws allow it).
I do wonder how much of this is psychological. I'm sure some people just have a sentimental attachment to pennies, but I would guess that most people who saw such a sign got upset about the idea of being short-changed, even by a few pennies, and never thought that it would also even out in their own favor at times.