$AllVMs = Get-VM | Where-Object { $_.ExtensionData.summary.config.ManagedBy.Type -ne "placeholderVm" }
$VMs = $AllVMs | select Name, `
    @{n = 'ProvisionedSpaceGBr'; e = { [math]::round($_.ProvisionedSpaceGB, 2) } }, `
    @{n = 'UsedSpaceGBr'; e = { [math]::round($_.UsedSpaceGB) } } 

$BisResult = [System.Collections.ArrayList]@()
$Clusters = Get-Datacenter Primary* | Get-Cluster 
ForEach ($Cluster in $Clusters) {
    $VMs = $Cluster | Get-VM -Tag "Test" | Where-Object { $_.ExtensionData.summary.config.ManagedBy.Type -ne "placeholderVm" }
    $Sum = $VMs | Measure-Object -Sum UsedSpaceGB, ProvisionedSpaceGB

    $obj = [PSCustomObject]@{
        Name               = $Cluster.Name;
        UsedSpaceGB        = [math]::round(($Sum | Where-Object Property -eq UsedSpaceGB).Sum, 2)
        ProvisionedSpaceGB = [math]::round(($Sum | Where-Object Property -eq ProvisionedSpaceGB).Sum, 2)
    }

    $BisResult.Add($obj)
}

$MdnResult = [System.Collections.ArrayList]@()
$Clusters = Get-Datacenter Secondary* | Get-Cluster 
ForEach ($Cluster in $Clusters) {
    $VMs = $Cluster | Get-VM -Tag "Test" | Where-Object { $_.ExtensionData.summary.config.ManagedBy.Type -ne "placeholderVm" }
    $Sum = $VMs | Measure-Object -Sum UsedSpaceGB, ProvisionedSpaceGB

    $obj = [PSCustomObject]@{
        Name               = $Cluster.Name;
        UsedSpaceGB        = [math]::round(($Sum | Where-Object Property -eq UsedSpaceGB).Sum, 2)
        ProvisionedSpaceGB = [math]::round(($Sum | Where-Object Property -eq ProvisionedSpaceGB).Sum, 2)
    }

    $MdnResult.Add($obj)
}

$MdnTotal = $MdnResult | Measure-Object -Sum UsedSpaceGB, ProvisionedSpaceGB
$BisTotal = $BisResult | Measure-Object -Sum UsedSpaceGB, ProvisionedSpaceGB