Sherwin Williams sells a two part epoxy paint for ceramic tiles. It has ether in it so be sure and have a good ventilations system.
The stuff is self leveling and does work well, but once you do this, you will be doing it often as maintenance.
Personally, I would not do it, I would tear out the tile and retile before I would paint my tiles. I have seen in the business world that it does not stay on permanently.
Think it over.
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