I ride the Ohio Turnpike every day to work. ($$$) I have a small Chase Harper barrel bag
on my handlebars that I use. I wedge the EZ Pass in so that it sticks up and out of the bag on the right side. I then close the zipper tight against it. This works as long as you're not riding on too rough of a surface. I did lose one once after hitting a hard bump, but have doing this every day for the past few years and it works. I also use the bag to keep a small can of chain lube, tire pressure checker and whatever else.