The book value for V1 is usually a balanced field figure, if you were doing the takeoff calculation manually, you would then find a weight decrement and a V1 decrement, with a proviso that if the adjusted V1 was below VMCG, then you had to round it up to V1.
There are three issues here, the first is your ability to control the aircraft laterally following an engine failure, this is the reason the V1 is rounded up to VMCG.
The second issue is the accelerate/go, as you have increased the V1, you have accounted for this.
The third issue is accelerate/stop, this is where it gets fun, if you are on a true balanced runway that gives a V1 of 102, and you have rounded this up by 6 knots, what guarantee do you have that you will stop on the runway?
Is it right to arbitrarily round V1 up by 6 knots? If this is acceptable on a contaminated runway, why can't we do it on a dry runway, why are we so insistent that V1 is a speed which you MUST HAVE initiated an RTO.
Mutt.