I have picked them up but lately, not. At one of the discount food markets here, to cut costs by not having an employee bring carts back from the lot, you have to put a quarter into the lock to free the cart. The assumption is you want that quarter back so badly, you will return the cart, lock it up and get the coin back. Lately, I've just given the cart to an incoming shopper, refuse their quarter & tell them to pass it on.
The earlier comments about back and knees precluding picking up pennies apply to me and once "freed" from the delusions about pennies, fortunate enough that I don't have to count them at least for now, I don't care about small change so much anymore.