Excel 2010 :: Summing Order Revenues Over Next Consecutive Calendar Days

I am using Excel 2010. I am tracking client orders on a spreadsheet. I would like to offer a 60 percent rebate on revenue from orders placed between the first order date and 30 calendar days thereafter. On day 31 and continuing through day 60, I would like to offer a 40% rebate. On orders placed on day 61 through 90, I would like to offer a rebate of 20%. From all of the orders placed by clients who start ordering on different dates, I need to sum their order revenue in these three time periods. I have the individual client order data arrayed on my spreadsheet - one order per row.

I am capturing the unique client ID number (Column A), the order date (Column B), and the associated revenue (Column C). Keying off of their unique ID number, I would like to calculate the sum of how much revenue is generated in calendar days 1 through 30, days 31 through 60, and days 61 through 90 from the very first order date from any given client. The start date can be any date in the month, so I can not rely on any calculation that uses the calendar month. Orders are not necessarily placed every day. Multiple orders may be placed on any given day, and then no orders may follow for many days afterward.