Not so easy
Buying five items, choosing one and sending the rest back? Do it often enough and you will regret it at some point.
Sooner or later someone is going to go bust, or have admin problems, or refuse to refund you, and you will have serious hassle getting your money back.
Or the item will get lost en route, or you will be out when it is delivered and find a note telling you to pick it up from a depot 20 miles away. Or you will open the package and find it is the wrong item, but try convincing the supplier...
If the items are stolen, damaged or destroyed while in your possession, you can't return them and your insurance, or card company, might a a little suspicious if you claim for 5 brand new laptops.
Do you think that all the CC refunds aren't going to affect your credit rating? Everything else does. And will a retailer carry on sending stuff out to you forever if you always return it? You'll be in a list, and if its a shared list eventually you won't be able to shop anywhere that anyone has heard of.
Mail order is a pain, placing five times the orders you need to is a world of pain.