I wouldn't actually ever do this, but...
My team at work are on a compressed hours working pattern, working 6 days out of 10. The tea club costs £6 for 3 months. I work part time, so I do 4 days in 10. WIBU to pay into the tea club on a pro rata basis, £4 every 3 months?
(I am not really going to squabble over 67p a month.)