Sales commission collusion can involve different parties.  For sales that did not occur, this may involve the sales rep and a customer order entry person, as could also be the case for over-inflated sales, though this can also be in collusion with the customer.  With sales returned by the customer, collusion could involve having the customer purposely make purchases with the intent of returning them.  Sales commissions should not be paid on pre-booked sales; rather, they should only be paid after the goods or materials have been shipped.