My problem with this is I what to group nodes by Name, Version, cellsize and refinement. So in the following the information which changes are refinement, runtime and CumulativeVol, could I get my desired output just by having?:

<VolumeReport>
 <Name>v_example.gri</Name> 
 <Version>1.0</Version>
 <Refinement>10</Refinement>
 <CellSize>
    <CellSizeX>500.000</CellSizeX>
    <CellSizeY>500.000</CellSizeY>
    <VolumeUnits id="m3">Cubic Metres</VolumeUnits>
    <CumulativeVol>147977918</CumulativeVol>
 </CellSize>
</VolumeReport>
<VolumeReport>
 <Name>v_example.gri</Name> 
 <Version>1.0</Version>
 <Refinement>4</Refinement>
 <CellSize>
    <CellSizeX>500.000</CellSizeX>
    <CellSizeY>500.000</CellSizeY>
    <VolumeUnits id="m3">Cubic Metres</VolumeUnits>
    <CumulativeVol>147751938</CumulativeVol>
 </CellSize>
<VolumeReport>
[download]

Desired output:

v_example.gri	Grid Refinements
Version 15.5	4		10
CellSize	Runtime	Volume	Runtime	Volume
(500.000,500.000)	10	147751938	12	147977918