So, paraphrasing your problem specification, I get this:

1. Rotate files from dir_1 to dir_2 every 5 minutes.
2. Rotate files from dir_2 to dir_3 every 5 minutes.
3. Rotate files from dir_3 to dir/main every 5 minutes.
4. and so on.

i don't think this is the problem statement. i think it's more like:

1. file arrives in main directory.
2. move file to one of three directories, alternate between dir_1, dir_2, dir_3

i could be wrong, of course.

~Particle *accelerates*