There's another nuance to this, and I thought it best to make another comment.

The original policy was that under $10 they must give you the first item for free, and all subsequent same items at the lowest posted price.

If the item was over $10, you would get a $10 off the lowest posted price for the first item, and every subsequent same item at the lowest posted price. This generally came into play when an item rang up $200 but maybe the sign said $170.

Which meant that you could find something that was incorrectly priced, and grab 50 of them. One time I bought 20 power toothbrushes that were incorrectly posted at $9 but were $79 a piece. You better believe I had a picture of the advertisement when I walked up to the till. The manager was hotter than the hinges of hell I can tell you that!!! They even paused for 10 minutes to go check security footage to make sure I did not post a fake price!

The other subtlety was that retailers who adhered to the policy did in fact have to have signage posted at the till. But it was on the customer to ask. If the customer making the purchase did not specifically ask to invoke the policy, nothing would be done.

I would compel people in line to specifically ask for the discount as the clerk stood there, following their training, that they are not to talk about it unless specifically asked! I made it my mission for like 2 years to let every human I know how to use the policy to their favor.

I'm kind of using advertised and posted interchangeably here, but generally I mean the posted price, either way it still applies.