Analysis :: Range Function - How To Get Last 60 Days Before A Month Starts

I am trying to get the last 60 days before a month starts. I have a set that is returned from the query below :

SELECT
   non empty
   [Measures].[TRANSACTIONS Count] on 0,
   non empty ([TRANSACTIONS].[Days].[Days],                                                          
                                     [TRANSACTIONS].[Transaction Month].[Transaction Month])  on 1 from [cube]   

I can get the cummulative count of last 60 days before month 2 by hardcoding the day of transaction of start of month like below :

WITH MEMBER
 [Measures].[Cumm Account Count]
AS
(
    AGGREGATE( [TRANSACTIONS].[Days].CurrentMember:NULL ,[Measures].[TRANSACTIONS Count])
)

 SELECT
   non empty [Measures].[Cumm Account Count] on 0,
   non empty [TRANSACTIONS].[Days].&[3]:[TRANSACTIONS].[Days].&[3].lead(60) on 1 from  [cube];
 
and for subsequent months by using the dates that the following month starts. How can I achieve the above result without having to use the day numbers, I tried to use the tail function (to get the months and star date) but it wont work because the range function  accepts members only...