Can you set custom ringtones for contact groups?

In iPhone, you can easily change the default ringtone (Settings → Sounds → Ringtone) and set a custom ringtone for individual people (Contacts → [some person] → Edit → Ringtone). But can you set a custom tone for a *group of contacts*? (E.g. "family" or "workmates".) I think that would be handy—and quite *basic* functionality, so to speak—but I couldn't find a way to do this through the iPhone UI. Is it possible at all (without jailbreaking)?