Can the Rebate Amount be calculated based on cost?

Question on rebates.

Can the Rebate Amount be calculated based on cost?  We see that it works based on sales amount,
but we would like to configure it based on cost?  We setup the adjustment (configured it for
rebate) and define a 3-Cost Basis code.
When we create the sales order the F4074 has the rebate adjustment
created based on cost.  However, when we
run it through sales update the F4078 and F4079 have the rebate amount based on
price