select * from 
  (select product_id, sum(sales_amt) as product_sales, 
  RANK() over(order by sum(sales_amt) desc) as 

  product_rank
  from sales 
  where customer_id in
    (select customer_id from
      (select customer_id,

      100 * CUME_DIST() over(order by sum(sales_amt) asc) as 
      cust_percentile
      from sales group by customer_id)
    where cust_percentile > 85)
  group by product_id)
where product_rank <= 5

order by product_rank;
 
PRODUCT_ID            PRODUCT_SALES             PRODUCT_RANK
-----------------     ---------------------     --------------------
SO-1278               3569871                   1
SE-9087               2998109                   2
SI-7652               2587397                   3

SD-0386               2001298                   4
CO-8925               1098763                   5