You can check the session and system level statistics, for example

SQL> create table t as select * from all_objects;

Table created.

SQL>
SQL> conn scott/tiger
Connected.

SQL> delete from t where rownum = 1;

1 row deleted.

SQL> commit;

Commit complete.

SQL> delete from t where rownum = 1;

1 row deleted.

SQL> commit;

Commit complete.

SQL> delete from t where rownum = 1;

1 row deleted.

SQL> commit;

Commit complete.

SQL> delete from t where rownum = 1;

1 row deleted.

SQL> commit;

Commit complete.

SQL> delete from t where rownum = 1;

1 row deleted.

SQL> commit;

Commit complete.

SQL> delete from t where rownum = 1;

1 row deleted.

SQL> commit;

Commit complete.

SQL> delete from t where rownum = 1;

1 row deleted.

SQL> commit;

Commit complete.

SQL>
SQL> delete from t where rownum = 1;

1 row deleted.

SQL> rollback;

Rollback complete.

SQL> delete from t where rownum = 1;

1 row deleted.

SQL> rollback;

Rollback complete.

SQL> delete from t where rownum = 1;

1 row deleted.

SQL> rollback;

Rollback complete.

SQL> delete from t where rownum = 1;

1 row deleted.

SQL> rollback;

Rollback complete.

SQL> delete from t where rownum = 1;

1 row deleted.

SQL> rollback;

Rollback complete.

SQL>
SQL> @mystat
Enter value for statname: user rollback

NAME                                                              VALUE
------------------------------------------------------------ ----------
user rollbacks                                                        5

1 row selected.

SQL> @mystat
Enter value for statname: user commit

NAME                                                              VALUE
------------------------------------------------------------ ----------
user commits                                                          7

1 row selected.

where 'mystat.sql' is just:

select s.name, st.value
from v$statname s, v$mystat st
where st.STATISTIC# = s.STATISTIC#
and s.name like '%'||nvl('&statname',name)||'%'

Use v$sysstat for global stats, and v$sessstat for session level statistics other than your current session.

"user rollbacks" is a measure of explicit calls to undo a transaction. Another area you could look at is rollbacks that were needed due to error, eg

SQL> declare
  2    x int;
  3  begin
  4    delete from t where rownum = 1;
  5    x := 1/0;
  6  end;
  7  /
declare
*
ERROR at line 1:
ORA-01476: divisor is equal to zero
ORA-06512: at line 5


SQL> @mystat
Enter value for statname: transaction rollbacks

NAME                                                              VALUE
------------------------------------------------------------ ----------
transaction rollbacks                                                 1

The delete worked, but I had to roll it back, because the subsequent code in the PLSQL block failed.

Only use you can decide whether the number of rollbacks is an issue, but I will say that the database is generally designed to perform best "moving foward", ie, change data and commit. It is generally more expensive to roll back a transaction than to commit one.