For incoming Leads, there are a few ways to assign these throughout your reps.
If you are simply looking for something to get started and rotate through a group of reps without conditions like territory or customer profile round robins - we recommend starting out with this Workflow.
As soon as you're looking for more advanced routing logic - check out Swantide's "Advanced Round Robin" that our customers use instead of or in tandem with tools like Chili-Piper or LeanData.
Setting up Basic Salesforce Lead Assignment
Deploy Swantide's Workflow for Basic Salesforce Lead Assignment - this will automatically deploy the two Lead formula fields that you'll need to rotate throughout a group of reps.
Once deployed, as a Salesforce admin, navigate to Setup in Salesforce (gear icon in the upper right-hand corner)
Search for "Lead Assignment Rules" and click into this option