Benford's law does not apply to some of those things! In particular not to expenses.
Benford's law only applies to things that experience exponential growth, things that obey a power law distribution, and things that are totals of random processes.
How could expenses not have a power law component to their distribution? Sometimes you're buying an expensive thing, and sometimes a cheap thing, and you don't buy something between $999 and $200 dollars nine times as often as you buy something between $199 and $100.
Yes, you will certainly get artifacts at the top of what you can expense. You will probably also get distortions at the bottom where you'll have some threshold of "not worth expensing." There will almost certainly be distortion around the boundaries, but as long as you have a big enough range you should be able to see a Benford's law effect in the middle.
1. Spotting odd things in MPs' expenses: http://blog.jgc.org/2009/06/its-probably-worth-testing-mps.h...
2. Spotting odd things in BBC executives' expenses: http://blog.jgc.org/2009/06/running-numbers-on-bbc-executive...
3. The Iranian election: http://blog.jgc.org/2009/06/benfords-law-and-iranian-electio...
4. New Age mumbo jumbo: http://www.jgc.org/blog/2008/02/any-sufficiently-simple-expl...