sequences in transaction blocks

I want to insert records inside a transaction block (BEGIN - COMMIT/ROLLBACK). If the transaction fails,
the sequence do not rollback and retain the new value.

This is the default behavior of sequences ?

I use the following table:

CREATE TABLE proceduri
(
procedura_id int4 NOT NULL DEFAULT nextval('proceduri_proceduri_id_seq'::regclass),
tip_procedura_id int4,
....
CONSTRAINT proceduri_pkey PRIMARY KEY (procedura_id)
)
WITH OIDS;

where 'proceduri_proceduri_id_seq is:

CREATE SEQUENCE proceduri_proceduri_id_seq
INCREMENT 1
MINVALUE 1000000000
MAXVALUE 1099999999
START 1000000001
CACHE 1;