By default if you as admin create special prices on products, these special prices are visible only on website. and that is all ok.

But when it comes to checkout, user simply see all products in cart/checkout the very same way. Without any sign that the item he just added to cart has a discount.

And lets face it that the big punch to buy or not to buy, to all of us (customers) makes the visual seeing of HOW MUCH we save money on the deal:) And once we see the BIG FAT price striped trough and changed with a small one.
We do not want to loose the deal:) and we buy.

So with the help of this extension you can you can influence the customer's decision to buy just by showing how much money he will save.:)

Nobody wants to loose a good deal.... And that is your change as a store owner to show it to your customers.