I also had the impression that breaks were 5 min. and that was why I was delightfully surprised when I showed up for the test and was told that they were 10 min. I was wondering how a person would even have time to go to the bathroom during a 5 min. break!
kryzak is completely correct, though, in that included in that 10 min. is the time it takes the proctor to come and escort you out of the room (at least where I went, you had to raise your hand and they came and got you), sign you out and then when you come back they rescan your fingerprint, escort you back to your computer station, and sign you back into the computer.
However, the breaks are optional. When I took the test, I think that I was the only one (there were about 5 other people there) who took any breaks. I'm just the type of person who needed to take some deep breaths and decompress a bit after each section.