Function where MIP will automatically calculate debit, credit amount for a percentage of an invoice

We receive grants that require a specific match percentage based on the particular grant. For example one of our current operating grants can be billed at only 14% of the invoice to WA ST DOT and the other 86% of the invoice is our match. I would love to be able to just type in 14% and have MIP automatically populate the debit box with 14% of the invoice. Then on following entry line, if I type in 86%, the debit box would automatically auto fill with 86% of the invoice total. This function would save me so much time.