FWIW, my experience with sending things to inmates is that about 85% of what happens to the package depends on who's in the mailroom that day. In California, things like books and tarot cards can only be sent through an approved vendor -- you can't just walk into prison with a gift.
If you send a deck through a vendor, it will arrive sealed. Whether it is opened and every card is scrutinized will probably depend, as I say, on who's handling the mail that day. I would bet that most mailroom prison employees wouldn't know enough about tarot to go through all 78 cards in search of contraband nudity.
That said, this is just my experience with California state prisons, and if any place is likely to have a prison employee who knows tarot, it's California.
And I still see new things every few months that boggle my mind -- enforcement of made-up rules, enforcement for the first time of rules I've never seen enforced anywhere before, unique and bizarre interpretations of long-standing rules, etc. Who knows what new wrinkle a tarot deck could produce! But all of this may be inapplicable to other states (I see Stovall18 is in Indiana) and county jails.