I was at my local Mitre 10 store today (Chelsea Heights, VIC) and noticed a sign stating that there was 20% off all paint from Friday 13/1 - Sunday 15/1.
I can't confim that it is at all stores, as I forgot to ask, but the large display poster didn't say it was just at my local store. There is no reference to this deal on their website.
I've been doing a lot of renovating recently and Mitre 10 sells paint at the same price as Bunnings, so it's a genuine bargain with the 20% off.
Happy painting!