Hi,
You can see your snapshots in DigitalOcean Control Panel.

Login, go to Images and you will see all your snapshots.
For now, there is no calculated prices of snapshots so have to do it yourself. I think I saw somewhere that they will add it in Control Panel by October 1st.

To calculate it yourself just sum sizes of all snapshots and multiple by $0.05.
You can see size in its column, next by snapshot name.

Also, yesterday DigitalOcean sent mails reminding about Snapshot billing, and they also sent how much it will cost you starting October 1st.

If you have more question be free to contact support, they are very kind to explain things like that :)

I think that billing for a service where the cost cannot be verified or checked is a little bit of a poor show.

If you want to bill for a service, the cost must be clear and upfront.