I would pronounce it as 'Tai-TAN-nee-a' as I heard it pronounced in an anime. 'Titania' Erza Scarlett from Fairy Tail is a very strong, heroic warrior, so I have a very good impression of this name :) Its relation to Titanium doesn't hurt either.
I pronounce my name Ti-TAWN-ya. And yes I did get made fun of sometimes for it but I go by my nickname Tia most of the time so I only get bothered when substitute teachers use my full name. But I like the name more than I don't like being made fun of for it.