stupic question: credit card processing

[slang]

I have a procedural question about the processing of credit or debit cards over the net and well, I did look for the answer, but not very much. Someone here must know for sure and maybe you'll save me some time.

If a business has a website complete with a products ordering page and CC processing, can a CC be used for a purchase at the store? For example, the shopingcart is used for ordering things from the online showroom. Could it be used to order and pay for something that will be picked up or carried out after the completion of the CC transaction instead of being shipped?

It seems possible that a special part of the online ordering could be for pickup items only, and therefore have no item description but just the note " item for pickup" in the shopping cart menu. When someone wanted to use their card for something in the real store, they would select the increments that would add up to the total of the purchase. 827.15 would be (1) $500, (3)$100, (1) $20, (7) $1, and (15) $.01 . The total of the items ( or dollar amounts ) would add up to the total when the CC user checks out. In addition to the CC transaction number etc, that you keep to verify the transaction for the consumers protection, the written sales slip would be marked as "paid by CC from website" or some thing similar.

This method would allow me to list the increments of the dollar amounts instead of listing every single item that is at the store. It would save me a lot of grief doing this.

Or would it?? I dont know.

Processing all CCs online would also avoid the duplication of having an online service and a card reader at the shop.

Somewhere in my travels I remember seeing a merchant doing this, but what, if any, problems might I have?