Report Builder Grouping issue

I am building what at first glance appears to be a simple report in report Builder using a simple query:

SELECT DISTINCT salesman, cust_id, invoice_id, date

FROM Sales

I created a table with a group by salesman, group by customers, count all their invoices, count all invoices for a specific item, and percentage of sales for those items out of all sales.

My problem is that when I group by salesman first, it limits the invoices to only those that belong to that salesman,  when what I need to return is all invoices regardless of salesman, like so:

Salesman        All Clients for this Salesman          All Invoices for these clients (regardless of salesman)        All invoices for Item#1   

Thanks

Lorna Robinson