Jango Fett states that he was hired by someone named Tyranus, e.g. Darth Tyranus - Count Dooku.
I think it's doubtful that Jango reported to or even knew about Sidious' plan for the Star Wars Universe. I think being a bounty hunter he was on a 'need to know' basis and he probably didn't 'need to know' who Sidious was.
In short, I think it's pretty obvious from the movie that he reported to Dooku.