yeah i've been doing this for a whilePnP.. u just set it in SmartShopper which has all your past purchases anyway.
They still print credit card &/or charge handling stubs as required by law. It makes things slightly faster in the longer month end shopping where you pay with contactless or qr and the packer was working diligently.
have to say i have hardly had issues with spam to any providers i've supplied an email for a slip