There are mangas that have tarot in it. I love them all, they're really good.
The Tarot Cafe is about an immortal woman who reads special clients at night with tarot. Tarot is all over the place. Each of the chapter has a page done with a tarot card of a well known tarot deck with characters from the manga instead on it. The readings use real tarot and are accurate, the author/artist does not make stuff up. We talked about this manga in other threads. Alas Tokyopop the publisher don't publish mangas anymore, which means their mangas are now very hard to find and expensive.
Count Cain & Godchild: Count Cain is a manga that came up first and the author/artist decided to make a sequel years later, so it's the continuation of the same story with the same characters. In these series a character Mary, the little sister of the main character, reads tarot cards. Also, the people in the evil organization all have tarot card titles and positions.
Fairy Tail: one of the side characters Cana, who is part of the wizard guild Fairy Tail, uses cards to read with them, they're not playing cards or tarot. She does divination with her cards, uses them as mode of communication, as a way to warn her that someone is in danger, and as a form of offensive magic. There is also a minor character at some point who uses playing cards to trap people in them.