The simplest way to do this is to just put SUM formulas in the right most column and bottom most row. Here is a sample.
http://www.syncfusion.com/support/user/uploads/GC_FormulasRightAndBottom_b024e9f2.zipBut this will not freeze the summaries so that they are always visible. If you want this, then one way to do this is to add another GridControl on the right and another GridControl on the bottom. You would then sync up the scrolling so things the grid scroll as one grid. Here is a kb link discussing how you might do this.
http://www.syncfusion.com/Support/article.aspx?id=10398