FoxHunter you are wrong. Maybe that's the way you did at your previous airline but many US airlines have been granted relief on this 10% so that there is no need to carry fuel for that period which might be over domestic airspace. Usually the 10% is limited to the time spent in Class ll airspace but ther may be other considerations.
FoxHunter is correct,
AFAIK.
The only "relief" for the 10% Reserve (which, FYI, the Europeans DO call "contingency fuel") is via a Planned Redispatch.