lo que sea... como sea da igual... no importa.. no me importa... all are accepted because you're expressing that something is not important or that you're not interested

da igual, me da igual como quieras could also be used this way

Si: "lo que sea"

Da igual. Es igual. Da lo mismo. Lo mismo da. (Even "lo mismo da que da lo mismo" jokingly) Es lo mismo. No importa. "I don't care" (you express your own indifference, not just the general unimportance of something) would be "me da igual", "me da lo mismo" or "no me importa". There are more slangy ways to say that (actually profanities, there are several Spanish equivalents of "I don't give a fuck"), but that's another question.