What you are looking for is fixed lot qty and that is not supported in Odoo.  Should not be to hard to develop.

It is possible to to set up reordering so they sort of act like this.  But it will not be consistent, and might result in a higher stock than you need:

If you want 200 as replenishment, set max qty to 199 and multiple to 200 it will replenish 200, as soon as the net stock is below min qty.  But if let say you get an order for 350, the result will be a replenishment of 400.

In Manufacturing there is a function to split manufacturing orders.  So if the result is a manufacturing order of 800, you can easely split it into 4 x 200.  Might help you.