When do Finns say jees, jes and jess?

Yes is kyllä or joo. However, in colloquial Finnish, you can hear Finns saying jes, jess and jees. What's going on with that? 

This is how I would explain it, but I'm also expecting to get some comments. Please share your experiences! :)

Say jess when you are really happy.

•  Jess! Tämä ei maksa mitään! - Yess! This doesn't cost anything. 

Jes can be almost any reaction.

• Mä otan teetä. - Jes. - I'll take tea. - Jes. 
• (Maksan) - Jes. (I'm paying.) - Jes.

I've heard people saying jes in situations where I could also hear ole hyvä or kiitos. Sometimes people use it instead of selvä to point out that they have understood something. You can also say jes while inhaling.

Kind of surprisingly, jees is good or great.

• Se oli ihan jees elokuva. - The movie was quite good. (Read more about ihan.)
• Se on tosi jees. - It's a great thing.

About the author of Random Finnish Lesson: 

My name is Hanna Männikkölahti. I am a professional Finnish teacher who gives private online lessons and simplifies books into easy Finnish. Follow this blog, if you want to be the first one to know when I post something new.  If you want to subscribe to my newsletter, you can do it here.