While the 5% saving is a good find, I think the savings can be better if you play the "game" harder. The two that come to mind are Dan Murphys & Woolworths Petrol.
a 5% discount at Dan Murphys is a good way to extend your savings, or as I see it "double-dip-savings" i.e you get the cheapest possible price locally, then the pure 5% off. Where as if you used the wish card at BWS or Woolworths Liquor then your purchase would be higher, even whilst using a 5% off wish card.
a 5% discount on fuel is where the real money can be saved IMOH, having 2 large Australian cars our annual fuel bill is ~$4,500 p.a, so paying with a wish card provides a tax free discount "profit" of $225. Fuel should always be purchased at the bottom of the pricing cycle to allow for the "double-dip-savings" Furthermore a 4cpl voucher "costs" via a purchase of goods from Woolworths, $30 spend per voucher, while a ~6cpl discount can be achieved without the supermarket spend at all...! (i.e 1.35cpl X 5% = $0.0675 cpl saving) I personally use the 4cpl discount taken as 2 QFF per litre and take the 5% saving from using the wish card, this comes close to "free" QFF points in my mind
Now if you can claim back the GST on your purchases, if you are a company or sole trader as I am, be it fuel or other, then the savings work even harder for you
you actually get to claim the GST of the full payment (as shown on the docket), although you paid 5% less with a wish card. A $2,000 purchase on wish cards that cost you $1900 will allow a $200 GST deduction, this is $10 more than would be claimed if paying the full amount with cash... Is this "free" money...?