cadman:Yabanize: If you buy top up's from the shop you would get the GST Reciept from the shop, if you bought it online you can get gst reciepts from the website
Very hard to get a compliant invoice from a dairy. And even most retailers only supply a thermal paper one which can fade within the 7 years you're required to keep records if it's a business expense.
If you're worried about fade take a photocopy of it like I do when i buy something that has a warranty receipt..