To use Time Machine to back up data and documents from your virtual machines, keep those files on the Mac.
When you use Shared Folders and Mirrored Folders in your virtual machines, you save your documents and data as files on the host, not in the guests. This means that although you exclude virtual machines from Time Machine backups, Time Machine can back up the files in the Shared and Mirrored folders because they do not reside in the virtual machines. See Enable Shared Folders or Mirrored Folders for a Virtual Machine
Exclude your virtual machines from Time Machine.