I found 2 tapes in the FNaF 1 map, 1 in the FNaF 4 map, 1 in the FNaF 2 map, and 2 in the new SL map though I am not sure if their locations are randomly generated, here's where I found them anyway. The tapes remain invisible until you come close to them, so if you don't see the tapes at first try moving a little closer.

FNaF 1:

(1) In Foxy's pirate cove above a scrapped piece of paper. (2) In the right hallway, in the closet over to the right a bit against the shelf, again hovering above some scrapped papers.

FNaF 4:

(3) In the room where you spawn there is a trash can in the corner to your right, in it is another tape. (4) Fun with Pluashtrap In the second hallway to the right.

FNaF 2:

(5) This one is ONLY obtainable as Mangle because it is on the ceiling, in the main party room up against Foxy's cove to the left.

FNaF SL:

(6) Behind Ft. Foxy's certains down to the left. (7) At the end of the left hallway.

I am continuing my search for more tapes in other maps. I'll update this post everytime I find a new one by putting the date in the header so you guys will know if I found a new one. Let me know if you guys found the tapes I listed!