insert multiple rows at once in a MySQL database

insert multiple rows at once in a MySQL database

I can't get php to insert multiple rows at once in a MySQL database.
I use the $sql = "INSERT INTO database (a,b,c,d,e) VALUES ('$a', '$b'
,'$c', '$d', '$e')";
I want to insert 5 rows at a time in the database, but it only inserts
every 5th record. For example: 1. AA 2. AB 3. AC 4. AD 5. AE I only