Question : backup file maintenance / cleanup.

Hi.
I have a daily backup which stores file everyday as  yyyy-mm-dd.sql.tgz
for example, 2010-07-20.sql.tgz
recently, i looked in and i have 70 gigs of backups at 300mb each. way too many backups.
Is there a feature in Linux which can delete all but the 5 previous days and last day of previous 3 months. I see it does some sort of log maintenance, so did want to have to write something if its already there.
Points to either solution: point me to program that does that, or script that does it.
files i expect to keep using my rules above are

2010-07-20
2010-07-19
2010-07-18
2010-07-17
2010-07-16
2010-06-30
2010-05-31
2010-04-30

because of the different length months i could change my requirements to an earlier day in the month.

Answer : backup file maintenance / cleanup.

find backups -not -name \*-28.* -and -mtime +5 -exec rm {} \;

That should do it