The german rulebook states that you split the dice pools "as evenly as
possible", which I intepret that there´s no rounding involved: If you split a dice pool of 8 between 3 targets, you can form pools of 3, 2, 2 (but not 5,2,1 or 3,3,3 or 2,2,2).
But TBH, we can hair-split the fragg out of the current state of FA attacks, but that doesn´t solve their main problem: They are just almost 100% mechanically inferior to the other firing modes. (
Unless you use Anticipiation, at which point they become extremely silly if the GM doesn´t have common sense and puts a limit on the number of possible attacks).
Against a single target, 99% of the times you are better off with burst fire: You get a +2 Bonus on your damage code, you only lose 4 points of AR and spend only 4 bullets. With a FA attack, you
could attack the same target multiple times, but due to the split dice pools, there´s a high chance to miss one or even all them - and if you don´t hit with at least 2 of them, your outcome is already worse than with a single-target BF attack (This is especially true for low-damage FA weapons like Autopistols. Their FA mode is pretty much pointless right now). Against 2 targets, burst fire is strictly better, as you still get a +1 damage on each attack. Against more targets, burst fire obviously doesn´t offer a "catch-all" solution, but when you use FA, your dice pool is already split down so much that you won´t hit anything anyways. I can somewhat appreciate that they tried to break the pattern and give FA a more distinct effect, but the math just doesn´t check out. FA in SR6 is just
flailing around your weapon wasting bullets.
My current houserule adds a damage bonus based on the number of individual attacks: +3 for a single target attack, +2 for a 2-target attack, +1 for an attack against 3 or 4 targets, no bonus for 5 or more targets.
Using Anticipation is possible, but only for 3-4 targets. Attack limit is obviously 10, but that´s hardly relevant once you put a cap on the Anticipation cheese.
I really hope that they do something with FA firing in the Errata, or at least add more options (Wild Dice, anyone?

) in the upcomming supplement. A return of (actual) suppressive fire would be nice, as well as "wide" bursts that are harder to dodge.