I've seen this (UK), albeit "round up to £x.00 and donate the change to charity", which <supermarket> will use to announce "We've donated £X million to charity".

▲

GJim 13 hours ago | parent | next [-]

Ah, the charity donations.

Esso petrol stations routinely ask for this, and the staff member ALWAYS clicks the 'no' button before you can offer your card.

Source: Somebody who drives around the UK a lot for work.

	▲	manarth 13 hours ago \| parent [-]
		B&Q are on the naughty list too (and the cashier also frequently clicks the 'no' button).

▲

account42 10 hours ago | parent | prev [-]

Interestingly I haven't seen the charity thing seen here in Germany for a while. I guess its because they all are asking if you have a customer loyalty card now (sometimes for both the chain-specific one and wider programs) and there is only so much they can ask for before the cost from lower throughput becomes significant.