D-IFF
As you interpreted it is the way we also saw it i.e anything under a fiver no receipt was required.
You could therefore claim to eat X number of Big Mac's throughout the day, all under a fiver and not have to produce receipts.
No one chose to do it as it was felt that it may IMPLIES something fishy is going on, but then again, with the way the rules are written I think you'd be ok.
PS Did you get my PM from a few days ago ?