Discount Needed

Apologies if this has already been discussed. I am relatively new to NopCommerce.

I want a discount to do the following:

If the customer currently has £250.00 or more in their basket then set a 2.5% discount off the total order value
If the customer currently has £500.00 or more in their basket then set a 5.0% discount off the total order value
If the customer currently has £750.00 or more in their basket then set a 7.5% discount off the total order value

Is there currently a way inside NopCommerce (version 1.80) to achieve this or would we need to custom write a new discount ourselves?

*Please note this is their current basket not the customers previous orders.

Any help would be greatly appreciated.

Thanks