> Though I guess there must be some sort of control since the station is depleting its stock of gas, so it's not like they can order more gas and say they didn't sell what they had... (or can it?)

Conveniently, I wrote a handy-dandy tutorial er..uh...answer to a question about money laundering earlier this year that addresses supply-chain management and other money laundering tactics.

On the other hand, having significant amounts of cash transactions makes it much easier to launder money from your criminal enterprises!