If your XML is always of the format in the example this should work:

my @vol = $doc->findnodes('//Volume[@VolumeCategory="6444"]');
for my $element (@vol) {
    my $parent = $element->parentNode;
    if ( $parent->nodeName eq 'Job' ) {
        $parent = $parent->parentNode;
    }
    print $parent, "\n";
    print $element->textContent(), "\n";
}
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If the format varies then you need to show that.

Note that you need to use ->textContent and not ->nodeValue to get the text value of the element.

Output:

<Test size="50">
    <Job tags="boo baa">
        <Volume VolumeCategory="L" MeasurementCategory="Real">0.063</V
+olume>
        <Volume VolumeCategory="cuft" MeasurementCategory="Real">2.2</
+Volume>
        <Volume VolumeCategory="6444" MeasurementCategory="Deal">2.2</
+Volume>
    </Job>
</Test>
2.2
<Test size="100">
    <Volume VolumeCategory="L" MeasurementCategory="Real">0.063</Volum
+e>
    <Volume VolumeCategory="L" MeasurementCategory="Real">0.063</Volum
+e>
    <Volume VolumeCategory="6444" MeasurementCategory="Real">2.2</Volu
+me>
</Test>
2.2
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