No?
[Assuming that you end up with the same quanta after the Spell is played, and when I say bolt I mean Fire Bolt]
If you play a bolt with 68 quanta, it does 7x3 = 21 damage. This is because it treats any number above 0 in the ones' digit as if it was actually another 10 quanta.
With 70 quanta it will deal 7x3 = 21 damage as well. This is because it does not treat the ones' digit as another 10 quanta unless it is above 0.