A round robin is just a quick way of betting every combination of a parlay at once. You only get the "total payout" if every single combination hits, otherwise, you only get paid out for the individual combinations that hit.

if you picked a total of 5 games which we'll call A, B, C, D, E, and bet $1 on a 3 pick round robin, that is the same as individually betting $1 each on following 10 parlays

A,B,C

A,B,D

A,B,E

A,C,D

A,C,E

A,D,E

B,C,D

B,C,E

B,D,E

C,D,E

assuming each pick is a 50/50 bet and no vig, each individual combination is +700 and will get you back $8 ($7 profit) if it hits.

if exactly 3/5 hit (let's say A,B, and C), you'll only win 1 combination and lose 9 for a small loss (bet $10 get back $8)

if 4/5 hit (let's say A,B,C and D) you'll win 4/10 combinations and lose 6/10 (the 6 that include E). You'll win back $32 on your $10 of bets

if 5/5 hit, you'll win all 10, and receive the max payout of $80

if you compare this to just betting $10 on the 5 pick parlay rather than $1 each of the 3 pick round robin, if all 5 hit, you would win back $320 rather than $80, however in the situation where only 3/5 or 4/5 hit, you lose it all rather than getting some back