Hi Zach,
There is no built-in property for this. But one way to do this would be to have a custom engine for finding the summary changes in a grid and change the style setting(backcolor) of the summary cell depends on the summary value. Below is a forum thread that shows you "How to find the Summary changes in a GroupinGrid?". Please refer the forum and let me know if this helps.
http://www.syncfusion.com/support/forums/message.aspx?&MessageID=54689.
Best regards,
Haneef
