Wordpress / WooCommerce - Recommended Backup Intervals?

I was wondering if anyone w/ a decent size e-commerce site could recommend how often to backup the database. I'd like to do it at least a couple times a day or even every hour, but at what point is it excessive?

I'm using wordpress, if you can recommend any worthwhile backup plugins it would be appreciated as well.

I use WP-DB-Backup for backuping my Wordpress database. I've set it up to make weekly backups that will be sent to me via email, but you can do backups on this plugin directly to your hosting, on the wp-contents folder.
Try it out. I recommend.