I heard that UCs just want you to maintain a 3.0+. Is this true?
It depends on the specific contract they give you.
And yes, they care about that last semester.
If you get accepted, it is only conditionally until you finish all your courses with the stipulations they require, submit your transcripts, and complete any other requirements. They could require grades C or better, B or better, etc.
They care about everything you do.