At Target on their clearance items: if the sale price ends in a 4 then you know that is the lowest they will go on that item. Don't wait if you want it, it will not go down any more.

At Sam's if you see a price ending in 1 then that item is being discontiued, seasonal item or another reason, and it is marked down. That may or may not be the lowest price though. I just stroll the isles and look for a 1 on the price. Sometimes I run into some really great deals. Today I got Turkey Tenderloin Mignon wrapped in Applewood Smoked Bacon, 6 - 7oz portions for $4.61. Can't wait to try and sadly the only box left.