Paying for Non-Existent Orders:

Someone posing as a deliveryman approaches the clerk in a convenience store and claims that the owner of the business has placed an order, and the clerk needs to pay for it from the cash register.  To make it look convincing, he presents the clerk with an invoice and a key he claims to be from the warehouse where he stored the items.  He receives the payment and takes off without actually delivering any goods.

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Protect your business: 

Inform your employees on the proper procedures for ordering and delivering supplies.  Notify them of the proper payment method.  Do not all your employees to make payment of anykind from the cash register.