Can anyone give me guidance on the SAVE MART/LUCKY WINWINEVENT game? I won many reward points but is there something I should know before redeeming?

In a prior game, a worker told me they do not work at self-checkout and it each denomination can be redeemed once per transaction (e.g. one 50, one 75, one 100, one 500).

Seems like I need to go through the regular line and buy something cheap each time.