publish only the value of the last or the first date of a month

[Anonymous]

Hi there,

I have a table with entries being added each day. For reporting purposes, I need to show a trend, taking the sum of the values entered on either only the first day of each month or the last day of each month. The dates are in date format, the values in numbers and then there are categories of properties I need to report on. simple table, yet I can't figure out how to write my measure to report the first / last date totals for each month. 

thanks!