...............................neither. Both examples should say "used to" (inured, OR accustomed). As FumbleFingers pointed out, this is not a question of tense. Of course If you said "I used to go to the beach (ie, I WENT repeatedly), but now I don't", that would be past tense, and also requires "used". The only way I could imagine the present-tense verb "use" in such a sentence is "I use the bus to get to the beach." Or (past and present) "I used to take the bus to the beach, but now I use my car." Note: You may hear people say "useto". This is an elision of "usedto". Because of this speech habit (dropping the d) you may have also seen "used to" incorrectly spelled as "use to". Even by people who claim to know English. It happens.
-------- to recap: regardless of meaning, there is exactly one spelling of this dual (triple?) idiom—"used to"; and basically one pronunciation in America—"Yoo-stoo". If you wish to distinguish between being merely (in the habit of/accustomed to) doing something, and becoming inured to something difficult or uncomfortable, write ( "in the habit of" / "accustomed to") or "inured" respectively. But in casual speech, for the latter case, say "I really don't like riding the bus, but I'm getting YOO-stoo-it." The "but" makes a contrary, which makes clear that you are tolerating an unpleasant situation. This of course would be written as "... getting used to it" as explained above.