Probably many people also figured this out, you have to have the ING 5% pay wave rebate card, you can use it together with the tell coles $5 off voucher.
Just purchase between $100 - $105, with the tell coles voucher you bring the total cost down to below $100, then you can use the ING pay wave card, total savings is almost $10
If your ING 5% rebate is about to expire, just go and buy a bunch of coles gift cards
if you use one of those tell coles vouchers the total (after discount) has got to be >=$100. you would also need to split the payment with say, $1 cash. i think people mentioned that you could split the payment using multiple pay waves. your mileage might vary. gift cards are probably easier
i've already run out and i bought $1k's worth of :( damn you masters and your specials! i've still got some coles ones left.