WITH CTE(BARCODE,WEIGHT)
AS
(
  SELECT 'aa11aa' AS BARCODE,6.927 AS WEIGHT
   FROM DUAL

   UNION ALL

  SELECT 'bb222bb' AS BARCODE ,5 AS WEIGHT
   FROM DUAL
)
, t (barcode, weight, summa_do6kg, summa_zarfzhdie_05kg, summa_s_nds, overload_parts, overload_tail)
 as (
select barcode, WEIGHT
     , 888.6 summa_do6kg
     , cast(null as number), 888.6
     , ceil((WEIGHT-least(WEIGHT, 6))/.5) overload_parts
     , mod((WEIGHT-least(WEIGHT, 6)),.5) overload_tail
  from cte
 union all 
 select barcode
      , case overload_parts when 1 then overload_tail else .5 end
      , null
      , 61.71
      , 61.71
      , overload_parts-1, overload_tail
 from t
 where overload_parts > 0
)
select barcode, weight, summa_do6kg, summa_zarfzhdie_05kg, summa_s_nds 
  from t
 order by barcode, overload_parts desc;