If you make a habit of using Extra Care Bucks at CVS or Register Rewards at Walgreens (Wags), then you often need to find a filler item to fully use your 'extra money'.
Extra Care Bucks and Register Rewards are like store money that you get when you buy certain advertised items. Each store has its own rules on how to acquire and spend them, but when you have that memorized, you can treat them as free money to buy whatever (almost) you want in the store. If you start using the free money, you will often need to pick up filler items to bring the total to an amount the register accepts.
Most people apparently grab some candy. I'd rather grab something I can actually use. Unfortunately, the best fillers are scattered all though the store. It's best to know exactly where a few useful filler items are for those times at the register when they say you are a bit short. That way you can run and grab something quickly.
Here are some easy, cheap drugstore fillers to buy instead of candy:
Hand sanitizer - Usually for 1.00 but sometimes for 50 cents.
Ramen Noodles - usually 39 cents each. I use the ramen a lot as a filler, since I do eat them.
You can sometimes get tuna fish for 19 cents at Wags using their store coupons and an internet printable coupon.
Anything from the clearance shelves (I like the 75 cent soups).
You can usually grab a cold beverage of some sort for under one dollar.
Anything from the trial size bins. I always look here. Sometimes you can find a really sweet deal. Once I found a travel bag with toothbrush, toothbrush head holder, floss and toothpaste for 99 cents.
Cans of cat or dog food. A can of Friskies is around 57 cents.
Sometimes there are cheap office supplies (like pens) or razors (2 pack disposables).
Carefree pantliners. Carefree are often on sale for 99 cents, and you can use one of the many 50 or 55 cent off coupons floating around. They are often in the stores themselves on tear pads.
A packet of Crystal Light To Go powder for 50 cents. Usually these are inside the cooler, on the door, in front of things like Gatoraid. Not all stores do this.
CVS often has a bunch of items that they advertise as 10 for $10. That means one item is one dollar.
Walgreens has some dried fruit boxes for one dollar, like raisins, prunes and tropical fruit mixes.
Both stores have a greeting card section selling 99 cent cards.
Of course, you can simply go over the amount by getting something you need anyway, preferably with a coupon. I have done this with bug spray, kitten chow and coffee filters. Lots of people grab staples like milk or eggs, and happily run over a buck or two.