USE pubs
SELECT PayTerms=isnull(s.payterms,'NA'),
       "Less than 10"=COUNT(CASE WHEN s.sales >= 0 AND s.sales <10 THEN 1 ELSE NULL END),
       "10-19"       =COUNT(CASE WHEN s.sales >=10 AND s.sales <20 THEN 1 ELSE NULL END), 
       "20-29"       =COUNT(CASE WHEN s.sales >=20 AND s.sales <30 THEN 1 ELSE NULL END), 
       "30-39"       =COUNT(CASE WHEN s.sales >=30 AND s.sales <40 THEN 1 ELSE NULL END),
       "40-49"       =COUNT(CASE WHEN s.sales >=40 AND s.sales <50 THEN 1 ELSE NULL END),
       "50 or more"  =COUNT(CASE WHEN s.sales >=50                 THEN 1 ELSE NULL END)
  FROM (SELECT t.title_id, s.payterms, sales=ISNULL(SUM(s.qty),0)
          FROM            titles t
          LEFT OUTER JOIN sales  s ON (t.title_id=s.title_id)
         GROUP BY t.title_id, payterms
       ) s
 GROUP BY s.payterms

Distribution
range     total    num
1-1       10038  10038
2-10       4032   1012
11-50       300    123
51-100       72      1
1000-9999  3040      2

with item as ( 
 select * from (values (  1,    10),
                       (  2,    20),
                       (  3,    30),
                       ( 10,   100),
                       ( 20,   200),
                       ( 40,   400),
                       ( 102, 1020)
               ) as T (site_id, visitor_id)
)

, ranges as (
 select * from (values (   1,    1),
                       (   2,   10),
                       (  11,   50),
                       (  51,  100),
                       ( 101,  200),
                       ( 201,  500),
                       ( 501, 1000),
                       (1000, 9999)
               ) as T (s,e)
)

select  concat(s, '-', e) as range, isnull(sum(visitor_id),0) as total, count(x.visitor_id) as num
  from       ranges  r
  left join  item    x on x.visitor_id between r.s and r.e
 group by r.s, r.e;

range    total num
1-1          0   0
2-10        10   1
11-50       50   2
51-100     100   1
101-200    200   1
201-500    400   1
501-1000     0   0
1000-9999 1020   1