averaging a total out over a month
 

I need to conjure up some demo data for a business plan.

I have a total "income" for a month. I am looking from some existing
utility or function to spread this total out over the days for a certain
calendar month. sum of all the days == total. Any ideas or pointers?
Ideally I could bias certain days such as every sunday to "tend" to a
higher amount, monday to a lower amount etc.

Pointers gratefully received.