Changing the size of log_buffer

[M.Shakeel Azeem]

I am using 10g on win2000 for testing purpose
and i am changing the log_buffer

SQL> show parameter log_buffer;

NAME TYPE VALUE
------------------------------------ ----------- -----------
log_buffer integer 11158528

SQL> alter system set log_buffer=5242880 scope=spfile;

System altered.

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area 138412032 bytes
Fixed Size 1247756 bytes
Variable Size 75498996 bytes
Database Buffers 54525952 bytes
Redo Buffers 7139328 bytes
Database mounted.
Database opened.
SQL> show parameter log_buffer

NAME TYPE VALUE
------------------------------------ ----------- -----------
log_buffer integer 7028736

I have changed log_buffer from 11158528 to 5242880
But when i restart the DB then i found log_buffer=7028736 instead of specified value(524288)
granule_size=4MB
What could be the reason?
Can anybody help me in this regard?

thanx in advance

[davey23uk]

the database will round things to the apprpriate level, thats all its doing

[M.Shakeel Azeem]

the database will round things to the apprpriate level, thats all its doing

thanx for ur prompt response but can u please give me more explanation
i hope u wont mind it
anyhow thanx a lot