I don't say that a lot and I think a lot of people don't say that either. People are usually more spontaneous and just tend to end a conversation without a lot of formalities. If it was nice meeting someone that's always implicit, so you might just greet the person friendly and say good bye with a smile, or wave or whatever feels right. People don't always say "Prazer em conhecê-la/o." and when they do sometimes it might come out weird.