HOW TO FIND SUM OF LAST 5 MONTHS CUMULATIVE SALES

How to calculate last 5 months cumulative sales?

LAST 5 MONTHS CUMULATIVE SALES =
CALCULATE (
    [Total sales],
    DATESINPERIOD (
        DimDate[FullDateAlternateKey],
        LASTDATE ( DimDate[FullDateAlternateKey] ),
        -5,
        MONTH
    )
)

syntax DATESINPERIOD

DATESINPERIOD(<dates>,<start_date>,<number_of_intervals>,<interval>)

we can also find last X months average by using the above function.