I don't play on Winamax, but when I read your post I e-mailed Support.
Their response was:
"Hello,
Thanks for contacting us here at the Winamax support team
In response to your query, it is difficult for us to give a thorough explanation of how our rakeback works in Winamax.
As you may know, this heavily depends on your poker style, on the number of players on the same table, among other factors.
On the other hand, we can provide you with the % rakeback linked to each VIP status.
We kindly ask you to refer to the attached documents to have a broad idea of how our rakeback operates in Winamax.
Thank you for your understanding.
Kind Regards,
Winamax Support team"
Hope this helps.