Well, my car is a hatchback and I have a stereo in the back, but I bought my car used and don't have the little cover thing that covers behind the back seats. (I hope SOMEBODY knows what I'm talkin about) So I kinda HAD to get tint or that ish would have been stolen THAT day.
It's illigal here (BC, Canada) to have ANY tint on the front windows so I didn't do anything there. But I got 5% on the back three. And I kinda wish I had only gotten 35%. I mean it's cool in some ways, you can come RIGHT up to my window with your hands around your face and you can't see into my car AT ALL. And it's cool when I think hot chicks are behind me at a light cause me and my buddies can just turn right around and look and they have no idea.
It does have dissadvantages though, at night, I can't see ANYTHING. And I once backed into my friends car, god he parked in a stupid spot, but ya it was my fault. I learned my lesson though, now I always take a good look behind me before I leave anyplace because once I get in the car I can't see anything. Note this is at night ONLY, during the day you can barely notice a difference.
The place I got it done at was AWSOME. A little expensive but, LIFETIME warranty. If it ever bubbled (i've had it over a year and not had the slightest problem) or even if I just do'nt want it anymore or whatever, they will fix it or remove it for free. In fact, I bet if I went in there and said the 5% was too dark and I want 35% they'd prolly switch it for free.
My sister got her tint done at the same place, and for some reason, her back window keeps scraping some little lines in it, and they keep replacing it for free.
ANYWAYS, sorry about the life story but I hope this was somewhat informative.
Cliffnotes: I do NOT recommend getting 5% tint, I would go with something around 35%. I also don't recommend getting any illigal tint, it is simply not worth the pain in the ass.