http://topbucks.com/programs.php
$20 per sign-up for 0-9 sign-ups in a pay period
$25 per sign-up for 10-70 sign-ups in a pay period
$30 per sign-up for 71-149 sign-ups in a pay period
$35 per sign-up for 150-349 sign-ups in a pay period
$37 per sign-up for 350+ sign-ups in a pay period