Is there a way to manage permissions based on a value in a field. For example I have a master list of store locations with who works at those stores, then I have a list of sales with each store location. I only want the manager to be able to see the information in the list that pertains to their store. Is this possible?
You can create SharePoint groups for each of the stores, then create an event receiver that sets the permissions dynamically on the item to the group belongs to the selected value based on the value in your field.
In your master list of store locations you shuld add a new field of type
Person or Group and set the corresponding group in this field. This will enable to look up the group easily in your event receiver. Add the managers (and their delegations / replacements) to the groups.