Sorry, Kriston! I didn't think you were hosting a junk food fest, I just noticed that the lying incidents you described were all food related.
Yes, he may well lie about other stuff. But my strategy with lying at that age was to reduce the opportunities for lying. If I knew that they'd done something wrong, I would just address the issue directly rather than questioning them about it and possibly giving them an opportunity to lie.
LOL! No offense taken here, Cathy.

Maybe just a little of my own potato chip-related guilt showing through there...

I think I just have a junk food junkie on my hands in a mostly non-junk food house. He's also my picky eater, so I suppose it's natural (though not okay!) that he'd break rules and even my trust to get what he wants. His big brother claims broccoli as one of his favorite foods. Not so with DS4.

I completely agree with you that not giving him the chance to lie is the key. But when he tosses his cheese out, I'm not sure there's any way around it...treat or no treat. More than anything I think he just didn't want to eat the cheese.