Isn't it obvious? They don't have to round up or down with cards. A bit hard to pay that 2 cents when our lowest denomination is 5c in cash and I'm pretty sure they have even stopped or will soon stop making those
1 & 2 cents – rounded DOWN to the nearest 10
3 & 4 cents – rounded UP to the nearest 5
6 & 7 cents – rounded DOWN to the nearest 5
8 & 9 cents – rounded UP to the nearest 10
https://www.accc.gov.au/media-releas...s-transactions