I can think of some expressions meaning 'have a nice day', but none of them is common. In those situations, some people make a slight bow without saying anything, and a few express their thanks. Anyway, I think it is common to say 'gochisousama(deshita)' to waiters, 'arigatou' to cashiers, particularly when you are glad for their service. Some people always say 'doumo', but this might sound a little too casual.