Turn off Data and still use GPS

[proplayer44]

I'm Canadian on Telus and I travel to the States a lot. I would like to use my TOM TOM when I'm there but I'll get charged Data roaming. Is it possible to use TOM TOM with Data turned off. I attempted to test it once when I was there. I turned off the data and opened TOM TOM and it worked, but then when I looked at the DATA settings again it was back to ON all by itself.