The tie-break rules are listed on the FIDE website, D.II.02 paragraph G.14:
The position of teams that finish with the same number of match points shall be determined by application of the following tie-breaking procedures in sequence ...
(a) the sum of Sonneborn-Berger points, which are calculated as follows:
match points of each opponent, excluding the opponent who scored the lowest number of match points, multiplied by the number of game points achieved against this opponent
So yeah, it's called Sonneborn-Berger, but it's different from the one you see in individual tournaments.
Let's see if this holds for the USA team:
GP OPP MP GP*MP
4 AND 10 (ignored)
3.5 SCO 12 = 42
3 ARG 14 = 42
2 CZE 14 = 28
3 SRB 13 = 39
2.5 UKR 20 = 50
3.5 IND 16 = 56
2 RUS 18 = 36
3 NOR 16 = 48
2.5 GEO 14 = 35
2.5 CAN 15 = 37.5
TOTAL: 413.5
We arrive at the same total.
(scores can be found here).