A 3 team round robin goes like this.
1) Pick 3 teams or totals
2) 3 - 0 pays 7.8/1
3) 2 - 1 pays .6/1
4) 1 - 2 or 0-3 and you pay 3 times your bet
So if you play a $100 3 team round robin the payouts are:
3 - 0 pays $780
2 -1 pays $60
1 - 2 loses $300
0 - 3 loses $300
Its the same as playing 3 two team parlays using 3 teams in all three combinations.
So if you have teams A, B, and C you are basically playing
a $100 par with A and B
a $100 par with A and C
and another $100 par with teams B and C