Create User Defined Bin Slicer with Parameter

Hi prattja9

With the new New Parameters menu, select Numeric Range.  It works with the link you supplied. (pbix: 2 - Choose SIZE of Bins.pbix)

Let me know if you have any questions.

pbix: prattja9.pbix

Does this help?  I changed  to COUNTROWS( DimCustomer ) to 

Count of Customers in each Band - by size - 2 = 
VAR _minAge = [Min Age]
VAR _maxAge = [Max Age]
VAR _bandSize = [What is Band Size Value]
VAR _AgeBandTable =
    GENERATESERIES(
        _minAge,
        _maxAge,
        _bandSize
    )
VAR _currAge = SELECTEDVALUE( 'Age Band'[Age] )
VAR _bandHead =
    MAXX(
        FILTER(
            _AgeBandTable,
            [Value] <= _currAge
        ),
        [Value]
    )
VAR _bandTail = _bandHead + _bandSize
RETURN
    IF(
        _currAge = _bandHead,
        CALCULATE(
            DISTINCTCOUNT( 'DimCustomer'[Employee ID] ),
            'Age Band'[Age] >= _bandHead
                && 'Age Band'[Age] < _bandTail
        )
    )

 pbix: prattja9.pbix