How to Calculate Cumulative Sum using EARLIER Function in Power BI

How to Calculate Accumulative Total using EARLIER Function in Power BI
EARLIER is a DAX function acts exclusively on row context,  and its purpose is to create a reference to a column value on an outer loop of the evaluation of the expression.  
It is commonly used in Calculated Columns during nested row by row iterations.
Syntax :
EARLIER(<column>, <number>)  
Parameters :
column : A column or expression that resolves to a column.
num :  A positive number (optional) to the outer evaluation pass. The next evaluation level out is represented by 1; two levels out is represented by 2 and so on. When omitted default value is 1.

Scenario :
Suppose we have the data in a Power BI Report as follows..

Note :
In the above table, the Measure [NetSales] is calculated using the below DAX Expression.
TotalSales = SUMX(FactSales,FactSales[Units_Sold]*RELATED(DimProducts[Unit_Price]))

Now we can calculate the Total Cumulative Sum, and Cumulative Sum by Month using the EARLIER Function as follows..
Cumulative Sum by Month :
MonthCumSales = CALCULATE(FactSales[TotalSales],
FILTER(FactSales,FactSales[Order_Date]<=EARLIER(FactSales[Order_Date])),
FactSales[MonthN]<=EARLIER(FactSales[MonthN]))

Total Cumulative Sum :
TotalCumSales = CALCULATE(FactSales[TotalSales], 
FILTER(FactSales,FactSales[Order_Date]<=EARLIER(FactSales[Order_Date])))
Result :

How Earlier Function Works :
The EARLIER Function, takes the first date value '1/5/2014' and compare it with other date values , checks for the specified condition (<= or >=) in the Filtered row Context, if the condition satisfies that value will be includes in to the Sum calculation. This iteration will repeats till the last date value. 

-------------------------------------------------------------------------------------------------------- 

Thanks, TAMATAM ; Business Intelligence & Analytics Professional 

--------------------------------------------------------------------------------------------------------