I keep seeing people talk about great fillers and such. Why is this and what are they?

A filler does two things. If you are using XX/XXX Q it not only helps you make it to that $$ amount, but you also need more items than Q's when checking out. So if you have 10 Q's then you want a few fillers so it won't beep.

Clear as mud?

From my interpretation of it, a filler can be either A) an item used to get your total up to a certain number so you can use a $$ off coupon (ex: if you are using a CVS coupon for $10 off $50 and need an item or two to get your total up to $50) OR B) an item you don't have a coupon for since places like CVS only allow the number of coupons you use to be equal to or less than the number of items (because CVS allows a CVS coupon plus a manu coupon on an item, we often find ourselves with more coupons than items so the computer won't let you use anymore of your coupons). A filler item, like a pencil or pack of pocket tissues or my favorite, a .99 greeting card, is cheap but ups your total number of items so all of your coupons can go through.

Couldn't have stated it better myself!!!!!!!!!!