Is this lease detail legal in NC?

[Matt W.]

Hi BP, 

I'm thinking of adding a detail to my standard NC lease that would encourage tenants to pay early. I have heard of others doing this but I wonder how legal it is.  I don't see why it would be illegal because it benefits the tenant.  It works like this:

Say $1000 rent is due on the 1st, late after the 5th, the late penalty is 5% so $1050.  I want to encourage my tenant to pay before the first, but not require it, so I stipulate an early payment bonus of 5%.  So if rent is paid before the 1st, its only $950.  

The way I see it, this is a win/win.  I use Cozy so I'm not sure how I would enact this plan.  I'm thinking I could do this "off the record" and basically send the tenant a $50 check every time they pay the full $1000 rent amount early. 

Has anyone tried this or a different plan? Any lawyers have a take on the legality?

Thanks!