how to create a dynamic filter based on grouping

[BrianLewis]

I have a table like this

Customer	product	total
abc	a	2
abc	a	3
abc	b	4
efg	a	1
efg	b	2

lets say, I put a filter to show me anything where the total = 2

so I get this table below (which is fine)

Table 1
Customer	product	total
abc	a	2
efg	b	2

but if I have a single value visual on the dashboard, it will show n/a. I get why it's showing n/a since it isn't grouped by anything, but how do I make it to show 4 without using the 'total' feature if I grouped it like the table?

total

n/a

I feel like need to do the following

1. create dynamic field that is grouped by customer/product and sum(total) 
2. have a filter for total to filter the field above to get a list of customers
3. use that list of customers to filter all the visuals on the dashboard

does this sound right? if so, how would I do that? if not, what would be a better solution?