Behodar:
I popped into Briscoes after work to get a thing or two. Alas, no sale on today.
When I got to the checkout, without any prompting from me, the cashier said "we don't have a sale on today, but bring your receipt back on the weekend and we'll refund the difference".
This might be common knowledge but I thought it was a nice touch to effectively teach the customer how to game the system.
Went back as suggested, bought a few more things, and still ended up with a $16 refund :D
But my favourite part is probably the line on the receipt stating "Inclusive of -$2.14 GST".