I want to work out quarterly planned and actual sales figures with minimal
data entry.

I have my profit which is a rolling sum, i.e. every new sale adds to the
total. What i want is to perform a calculation based on the date on my
profit. When it is the end of the first quarter my calculation is performed
and the results appear. This works fine. What i then want to do is freeze
that result so that it does not update when i make my next sale so that i can
look back and see where i was last quarter. Any ideas on how to do this? I
have tried to simplify it, but what i want is to see at the end of the year
what my sales profit was at the end of each quarter without lots of data
entry.

Thanks,