BWAAAAAAHHHHHHhhhhhhhh ha ha ha ha ha!!!!
(I didn't even NEED to post to BWAH on THIS thread!)
Get a SIX POINT SOCKET and "HAMMER" it onto the bolt head if you have "dinged" the hex points up a bit. (An IMPACT socket will often do the trick... they are also usually toleranced with LESS clearance, so they should GRAB the hex head "snugger".

)
Don't forget, CHEAP 12 POINT sockets are toleranced VERY "forgivingly" most of the time... INCREASING the chances of "rounding" points on a hex head.
BUMP to using a BREAKER bar at that point. MAKE SURE you have AXIAL ALIGNMENT with the BOLT and your SOCKET as well... even just a LITTLE SKEW and you can ROUND heads terribly.
If ALL that doesn't work... get out a small jewelers file or Dremel tool and carefully craft the NEXT SIZE DOWN hex head out of the rounded one. THEN use the correct HIGH QUALITY SIX POINT socket to remove, as you should have done in the FIRST place.
...just my thoughts.
Oh, yeah... one last thing. DON'T BE PUTTING THE "LUBE" (whatever kind you employ for PENETRATION) on the HEAD END of the bolt... place it on the THREAD end ONLY!
ALSO, you can often "BREAK THREAD" by RAPPING on the head or any exposed threaded end with a hammer and something to strike with... however, if you rap on the threaded bolt end, DON'T used something that will "deform" or "flare" the bold/threads and make it worse.
Good Luck.
-crisp
