You get a time bonus for beating the target time on a level. For most levels, this is really, really hard as the target time is very low.
However, you can easily do this on level 1-3: As soon as the level comes up, draw powder from the fire to the keg by the safe. Ignore all of the pigs. You should get a time of 5 seconds; well under the target of 12 seconds for this level.