Imagine you are in Woolies doing the grocery shopping. You look at your Woolies IPhone App and it tells you need some Weet Bix, priced at $5.49, so you wander in the direction of the cereal aisle to grab a packet.
When you arrive at the shelf a funny thing has happened. The Weet Bix price ticket now says $5.51. 'Strange' you think to yourself, but you don't worry too much. It's only 2 cents after all.