My 2005 F150 has started squeaking very loudly as I drive. When I tap on the brakes it sometimes will stop. My brakes are fine however.

 

I had this happen in my 04, the rotors needed machined. Take it to a brake shop, the charge shouldn't be too bad.

 

Perhaps the last time the brakes were relined the mechanic left out the anti-rattle clips or pads.

 

Don't rule out wheel bearings. I just had one go bad on my 04 (05 has same brakes) at 54k miles, which caused a horrible squeal, especially when turning. Applying brakes had no effect. I had to replace the whole hub which happens to include the rotor...they are one in the same. Best of luck!