I bought some tiles at Lowes, and the employee there showed me some unglazed tiles that he would recommend for baking. But since he didn't have any experience or people asking him, I searched online for some info on the tiles.
So far I found out an answer to my question.
Do I need to seal the Rialto, Botticino, Positano or Murano series tiles carried at Lowe's?
No. During production process there is glaze incorporated in the mixture to help prevent stains.