Access Report Grouping

Ok, I have been racking my brain about this and cannot figure it out, I'm
still pretty new to this so it may be obvious.

I have a report that shows:

[Account Number] [Error Code] [Date] [$100]

[=sumof[$100]]

So everytime there is an account error there is a charge of $100. And total
charges are shown at the bottom of the form, that all works great.

Recently I found out that the client can only be charged $1000 dollars per
day total. So now I want the report to show a total but it cant include the
charges that went over $1000 per day. I thought about grouping the report by
day and then have a group footer with a charge for that day but I dont know
how to stop it from adding at 1000 dollars.

Thanks very much for any help / advice that you can offer.

James O