-- Create table
create table TREE_TAB
(
  id     NUMBER not null,
  par_id NUMBER,
  name   VARCHAR2(5) not null,
  amnt   NUMBER not null
);

Insert Into tree_tab (id, par_id, Name, amnt) values (1,null,'a',100);
Insert Into tree_tab (id, par_id, Name, amnt) values (2,null,'b',100);
Insert Into tree_tab (id, par_id, Name, amnt) values (3,1,'aa',10);
Insert Into tree_tab (id, par_id, Name, amnt) values (4,1,'ab',10);
Insert Into tree_tab (id, par_id, Name, amnt) values (4,1,'ab',10);
Insert Into tree_tab (id, par_id, Name, amnt) values (5,1,'ac',10);
Insert Into tree_tab (id, par_id, Name, amnt) values (6,2,'ba',1);
Insert Into tree_tab (id, par_id, Name, amnt) values (7,2,'bb',1);
Insert Into tree_tab (id, par_id, Name, amnt) values (8,4,'aba',1);
Insert Into tree_tab (id, par_id, Name, amnt) values (9,4,'abb',1);

With a As
 (Select row_number() over(Order By 1) rn, Level, connect_by_isleaf leaf,
				 t.id, t.par_id, t.name, t.amnt,
				 (Select Sum(amnt)
						 From tree_tab x
					 Connect By x.par_id = Prior x.id
						Start With x.id = t.id) sum_sub
		From tree_tab t
	Connect By t.par_id = Prior t.id
	 Start With t.par_id Is Null),
b As
 (Select Name, amnt, id, par_id
		From a
	Union All
	Select 'Итого по ' || Name Name, sum_sub, Null id, id par_id
		From a
	 Where leaf = 0)

Select Name, amnt
	From b
Connect By b.par_id = Prior b.id
 Start With b.par_id Is Null
 Order Siblings By id Nulls Last