Question: I had my first session as Dungeon Master (DM) yesterday playing pathfinder ("First Steps In Lore" from the "Pathfinder Society" series) with a group of first-time tabletop RPG players (myself included). Overall the sessions went well, a good crash course for everyone and everyone seemed to enjoy themselves.

My question is a problem I personally had while DMing. I taught the players that they can roll for perception to check things out, finding traps and secrets, etc. The players got the idea and started saying "roll for perspection to check out the room", etc., and they found a couple of traps that way, and that's fine. The problem I had was: What do I do with all the "useless" rolls?

Most of the time they were rolling when there was nothing to find. Even on a natural 20 I kind of just described the room in more detail while saying something like "but there is nothing of interest".

Is there a better way of approaching this? Do I make something up?

I'd like to add: I would prefer my players roll their perception checks when they are actively looking. I am not a fan of the hidden-DM-rolls-for-all-perception idea.

Answer: 
have the players roll a bunch of perception rolls at the beginning, list them all and cross them off as you go, they know the rolled them, but have no idea if they see nothing because of a bad roll, or if there is truely nothing to see.
The situation should be handled exactly as if there were something interesting to find but they did not meet the DC for finding it. That is effectively what happened, just in this case the DC is infinite as there is nothing to be found. 

Explicitly telling the players that there is nothing to be found should be avoided - if you get in the habit of telling them that there is nothing to be found, they will know when they have merely failed the roll.