how to execute multiple Invoke-Sqlcmd in one transaction?

I would like to perform a bunch of invoke-sqlcmd in one sql transaction. Here's what I'm doing:

try{
   $scope = New-Object -TypeName System.Transactions.TransactionScope

   GetFiles $SqlFilesDirectory

   $scope.Complete() 
}
catch{
    $_.exception.message
}
finally{
    $scope.Dispose() 
}

Here's how GetFiles is defined:

    #
# Get SQL Files recursively
#
function GetFiles($path = $pwd) 
{ 
    $subFolders = Get-ChildItem -Path $path -Directory  | Select-Object FullName,Name | Sort-Object -Property Name 
    $sqlFiles = Get-ChildItem -Path $path -Filter *.sql | Select-Object FullName,Name | Sort-Object -Property Name
    
    foreach ($file in $sqlFiles)
    {
      Write-Host "file: " $file.Name
      Invoke-Sqlcmd -ServerInstance $ServerInstance -Database $DBName -Username $SvcAdminAccount -Password $SvcAdminPassword -InputFile $file.FullName -QueryTimeout 65535
    } 

    foreach ($folder in $subFolders)
    {
       Write-Host "`nGetting files for subfolder: " $folder.Name
       GetFiles $folder.FullName
    } 
}

How do we perform a series of invoke-sqlcmd in one transaction?

Here's the output:

The behavior that I want is that ALL changes are rolled back if a single sql script fails.