The $5 Challenge

I've been seeing this little beaut everywhere but didn't think I'd be able to do it for a few reasons. a.) I don't carry cash that much b.) I really love carrying small bills around c.) I haven't served at night in a while.
Well.... Because of some up and coming changes, and the fact that I love where I work at night, I will be working nights again to make money. And tips are the best place to get a variety of bills. I worked last night and only took home one, but it was then and there I decided to do this.
What is it you're asking?? We shall call it the $5 moolah challenge. How does it work? It's super simple: every time you find a $5 bill in your possession, set it aside  until the end of the yearish... DON'T spend it!

Now I'm going to change the rules a little for myself: If I get money out and exchange for smaller bills, that does not count. It's when I get change or what not. I do love 5s- easy to get coffee with etc... So I feel that I should be able to spend the 5s I take out. But if I want to put it in my jar at the end of the day, I definitely will!
People have said you can save $1000s a year by just saving 5s.

And it's a challenge for me not to spend $$ that's just laying around. I can't wait to see if I can do this. 
What do you think about this challenge??? Something you'd be interested in too??
Also I need your help!! I want to get the perfect Valentine's Day card for Dan but can't decide!! You can help me HERE!!
Ta ta for now <3