Hi jmoranfun123! I bought my ceramic tiles at Citi Hardware. They have a lot of variety to chose from. You may also try Negros Building Supply Depot Inc. its near the street intersection in going to Robinson's Mall.
I agree with the Citi Hardware option for a couple reasons. They have the best return policy in the city (they will take back extra tiles or replace broken tiles without hassle), you can pay by credit card without a surcharge, they have a good selection at reasonable prices, and there is a good chance that they will still have some stock of the same tile if you are short a couple pieces. On the down side, like everywhere else, they do run out of some brands and models, and I would stay away from some of the cheaper brands unless you don't care about colour and size variations between batches (I ended up with three different colours of the same tile in my bathroom). Rejoice Hardware (the tile store is located across the street fromthe main store) on Cervantes Street also has a good selection. There is also a big tile store /motorcycle shop just next to the airport with another branch on the South Highway (dont know the name) not far outside the city but I didn't like the selection, mostly chinese, and the prices weren't much better than elsewhere.