问如何在PowerShell一个对象中用多个项进行求和？

$report.gettype().name
Object[]

echo $report

Item                       Average
--                         -------
orange                     0.294117647058824
orange                    -0.901960784313726
orange                    -0.901960784313726
grape                      9.91335740072202
grape                      0
pear                       3.48736462093863
pear                      -0.0324909747292419
pear                      -0.0324909747292419
apple                     12.1261261261261
apple                     -0.0045045045045045

echo $total

orange  -1.5097
grape    9.913
pear     3.423
apple   12.116

$tmpPrev = ""
foreach($r in $report){
    $tmp = $r.item
    $subtotal = 0
    if($tmp <> $tmpPrev){
        $subtotal += $r.average
    }