It's both.
The canonical translation I would use for "
Me da igual" would probably be "
It's all the same to me," but it can also be translated as "
I don't care" ("
No me importa") or "
It doesn't matter," ("
No importa") etc.
I think the usage you described is common. Another translation of "What do I care if..." might be "¿Qué me importa si...?" but that's a lot stronger sounding than "me da igual."