With Sharing Enabled among peers - How to hide specific Leads?

With Sharing Enabled among peers - How to hide specific Leads?

We have Leads/Contacts/Accounts Sharing enabled among peer group of users. So sales people can see what's everybody is doing.

With sharing enabled - Is there a way to hide Individual Records (e.g. individual Leads, specific Contacts, specific Accounts or Tasks)?

To reiterate - we want data sharing enabled by default, but with ability to mark specific records as private - so they are not visible to others.

Is that possible?

Any insight is much appreciated!