Sum column based on Multiple Parameter

Hi guys,

I have a datatabel like this

Custmer count = the total number of customer with the assets on the right.

I have also created a field paramter 

Parameter = {
    ("Mutual Funds", NAMEOF('DataTable'[Mutual Funds]), 0),
    ("GIC", NAMEOF('DataTable'[GIC]), 1),
    ("CASH", NAMEOF('DataTable'[CASH]), 2)
}

I am able to connect both with the paremeter (solution provided by ExcelMonke )

CustomerCount = 
VAR _MF = CALCULATE(SUM('DataTable'[Customer Count]),FILTER('DataTable',NOT ISBLANK('DataTable'[Mutual Funds])))
VAR _GIC = CALCULATE(SUM('DataTable'[Customer Count]),FILTER('DataTable',NOT ISBLANK('DataTable'[GIC])))
VAR _SGD = CALCULATE(SUM('DataTable'[Customer Count]),FILTER('DataTable',NOT ISBLANK('DataTable'[CASH])))

RETURN
if(
    HASONEVALUE(Parameter[Parameter Order]),
    SWITCH(
        VALUES(Parameter[Parameter Order]),
        0, _MF,
        1, _GIC,
        2, _SGD     
    )
)

Thus now,  i select Mutual fund on the paramenter, it will have Mutual fund = 20 and total customer with Mutual fund = 1+3+3+5 = 12.

However, May I know if someone cann show me a trick how does it work with two or even three parameters?

For example, 

Mutual fund = 12 customer

GIC = 11 customer

Cash = 12 Customer.

Now I want to see how many customer I have with both GIC and Cash, so I multi-select both.

The total is 40 and customer count is 3+3 = 6 (because only these 2 groups of customer have GIC and Cash at the same time).

Any tips & tricks are appreciated!

Thank you