jQuery Grid Plugin – jqGrid

Hi, I´am working with treeGrid and i have different levels, is there a way to sum this levels?

Something like that:

–level0 ———–   78.00 (i need total of levels1)

         —level1 —   37.00  (i need de total of childs here!!!)

             —level2 – 10.00

             —level2 – 12.00

             —level2 – 15.00

         —level1 —-  41.00 (i need de total of childs here!!!)

             —level2 – 20.00

             —level2 – 20.00

             —level2 – 1.00

I´ve read some about method "getNodeChild" but i don´t know how to use it.

Some body have an example??

thanks.

EAR