Getting data in a query on last date of all previous months

Dear Experts,

I need your help with a query.

I am trying to create a query which when run should pick the number of Open Sales Order on the last date of all the previous months from the start of company.

I could create the query for fetching the required data on last day of the previous month, say today is 25th June 2014, so my query only fetches data for May 31st 2014 but I need data for all previous month, May 31st 2014, April 30th 2014, March 31st 2014 & so on.

Please advise how to achieve this is SQL query.

Thanks & regards,

Nitin