cost allocation to dimension values.

I have one dimension called Project. The dimension values are say, AAA and BBB.

Now I want to to distribute 95% to AAA and 5% to BBB for any invoice amount, or whatever transaction is being done.

Can I set somewhere in Chart of account for every account that 95% should be allocated to AAA and 5% to BBB. So that whenever there is a transaction, It is done automatically.

Prompt reply is expected.