For FY07 XOM's profit margin was about 10%. Their tax rate for that year was a ridiculously high 42.4%, so Uncle Sam took nearly $30 billion from them in '07.
Selected profit margins from other leading companies for FY'07:
Lockheed Martin, 7.25%
PepsiCo, 14.33%
Apple, 14.56%
Toyota, 6.53%...