Just noticed in the current Woolworths flyer that they are giving Woolworths Reward Dollars on iTunes card purchases (note - does not include the $20 iTunes card). Buy a $30 iTunes card and earn $6 reward, $50 card earns $10 reward and $100 earns $20.
Obviously not as good as a straight 20% discount (as you are forced to spend the savings) but not too shabby. Pity they didn't do it for Google Play cards as I've been spending big on those recently.
Why not just buy the card in Officeworks? iTunes cards are always 20% off in Officeworks.