Coming out to parents can have tragic consequences so be very careful. One thing you need to remember is that from the moment of our birth, our parents have preconceived ideas about us, our education, careers, weddings, etc. They also brag to others as any proud parent would do, they raise us, and mould us their way, we are the fruits of their toils. Coming out to them that you are TS can be understandably devastating for them.
That being said, many here have had to go through that risk and came out to our parents with varying degrees of success. Mine went very well. One approach you could take to test the waters so-to-speak would be to tell a little tale, and see how they react. For example...
"Hey mom/dad did you read that new paper article where that girl wants to change her sex and become a boy, I think they call them transsexuals, I wonder what her parents did?"
A little clumsy maybe but their reaction may give you a hint on how they may react if it were you. Remember that many folks have 2 belief systems, for example they fully support human rights, abortion, gay marriage etc, but on the other hand "Not in my back yard".
I could use my daughter as an example. We raised her to be respectful, and accepting of all types of diversity in the world, but when it came time to accept me it was a different story, and her reaction surprised both myself and her mom.
Just be careful and plan for the eventualities, good, bad, or otherwise.
Steph