Is there any benefit to collecting treasure in Return to Castle Wolfenstein?

As far as I can tell, there's no benefit to gathering treasures, besides that warm fuzzy feeling you get when you find all the secrets in the game.

There are some secret areas that contain weapons and/or ammo, but the "treasure" you find doesn't seem to effect the outcome of the game in any way whatsoever.

I have found that when you collect the treasures and visit the secret areas, they may be exchanged for bonuses at the end of a significant level. The bonuses include extra ammo, protections, health points, etc. But they are a little expensive, and may be used only a limited number of times.