Sumif with conditions?

I have a table, in the table are cost and an X in a column of who the cost is accociated with. on some lines it is split between multiple people. So I want to split that cost between the people in my totals for each person. Its a christmas list.

Example. 

DESCRIPTION, Cost     , Tom, Beth, Mom, Dad,
Visa Giftcard , $50.00  ,   X  ,   X  ,        ,      ,
Laptop         , $400.00,       ,       ,    X  ,   X  ,

Dad = $200.00
Mom = $200.00
Tom = $25.00
Beth = $25.00

Thank you for the help