Question about Rebatewager parlay payoffs ?

[Doug]

I did a test one here to check the payoffs. I got 278.01 with two different calculators, but $235 at RBW. Why is this ?

WagerType:PARLAY (6 TEAMS)
Date: Team:
Oct 15 MLB [901] NY YANKEES o8-115 [C SABATHIA -L/C WILSON -L]
Oct 15 NHL [1] COL AVALANCHE o5½+105
Oct 15 NHL [4] NY RANGERS u5½-105
Oct 15 NHL [8] PIT PENGUINS u5½+105
Oct 15 NHL [12] ANA DUCKS u6-125
Oct 15 NHL [13] VAN CANUCKS o5½+105
Risking 5 USD To Win 235 USD