WOW, I was just reading an article about repairing paper and will be interested in what people might recommend. My idle thought would be to put it on a glass surface and wet it thoroughly for a few days and then try to carefully beat and feather the edges so that they intermingle again...let's see what others say.
Not sure how much value that note is ? but for $4 i guess it would be a pretty cheap Experiment...LOL, the first thing i would do is put the note on a hard flat (non flammable) surface and take a warm not hot iron to it flatten it out and then depending on the joined surface run a very small bead of glue in the center and On the leading edges kind if like tac welding, wipe off excess and then put in a book over nite and repeat the process adding the adhesive in the areas you didnt before until the repair is complete
The article I was reading suggested using some other paper that was so thin it was almost transparent, wetting everything, applying a thin strip of the almost transparent paper along the tear and then letting it dry. Oh yeah, and using some wheat starch in the water.
Many factors go in to doing this the right away, including the correct paper if you can find something that is the same or close to it ?