LOOKUPVALUE Nearest not exact

The thread you referenced is not the same issue. 

What if the "Search_Value" that we use in the LOOKUPVALUE column does not exist in the "Search_columnName". I'd like it to return the closest value in the "Search_columnName". 

In the original question 1.12 does not exist in our lookuptable but we want it to return 0 since that is the closest. Here is another thread which mentions a potential solution: https://stackoverflow.com/questions/52525377/return-top-value-ordered-by-another-column

You can modify the formula to find the closest value. Here is the result I came up with:

Closest Match Measure =
MAXX (
    TOPN (
        1,
        LookupTableName,
        ABS (
            CALCULATE (
                SUM ( 'DataTable'[SearchValue] ) - SUM ( LookupTableName[ReturnValue] )
            )
        ), ASC
    ),
    LookupTableName[LookupValue]
)

Basically we are just finding the smallest difference between our value and the values in the lookup table, and returning the result. 

Note that the above formula may need to me modified depending on whether you have relationships between your tables. I have found that storing the measure as a variable works in these situations

Closest Match using VAR =
VAR myMeasure = [MeasureName]
RETURN
    MAXX (
        TOPN (
            1,
            LookupTableName,
            ABS ( CALCULATE ( myMeasure - SUM ( LookupTableName[ReturnValue] ) ) ), ASC
        ),
        LookupTableName[LookupValue]
    )