Need some help

I know some people do what you are doing, but unless all 10 songs were recorded exactly the same, as in a real band in a session, there is no real reason to treat each song the same. 
I treat each song as an individual. I use my ears for mixing and at this point I'm not fussing with overall Mastering details, That is a completely different step. I then then export them as a stereo 44.1 file. 
I do final touch ups in Wave Lab such as average RMS level and trimming tops and tails. 
Using a wave editor and working with stereo files makes this step much easier and gives you better control. 
You could use Sonar in a pinch if you don't have a Wave editor for mastering but your still going to want different settings for your mastering efxs anyhow. The only advantage I can see to having all 10 songs on the screen is to save time re loading each file to a fresh project that is just the stereo tracks. I know some bring the song back into the original project but to me this is all very inefficient. 
 
I know Sonar can do wonders with Mastering, but once you've used a wave editor such as Wave lab or sound forge, you would see what I mean about the right tool for the job. I don't believe Sonar can give you average RMS levels? 
Sonar is my Multi Track Sequencer
Wave Lab is my Mastering 2 track deck 
 

Try moving the plug-ins from the master buss to your stereo track for your first song and leave the effects bin of the master buss empty ... and then set-up the plug-ins for the remaining 9 stereo tracks individually.
 
Alternatively, leave only the limiter (or whatever your secret ingredient is) in the effects bin of the master buss and have individualized plug-ins in the effect bins of the 10 stereo tracks.
 
Either that or use Wave Labs.

Thanks Dave & Scook. Dave, I just realized your suggestion yesterday. Thanks a bunch guys.