Feature request: Add Option to round the time

[tuxflo]

I think it would be good if redtimer could automatically round time to "easier" values.

For example: I stop the timer at 4h:56m it saves 5 hours, if I stop the timer after 0h:48m it just saves 0.75h (45 minutes).

That would make my time accounting much easier :)

Of course this shouldn't be the default since I guess lots of people want the "exact" time values, but maybe this could be added to the settings menu. Maybe with a threshold setting at which point the values should be rounded.