Configure Special Price navigation step like Price
I'm working on Magento 18.104.22.168
In System > Configuration > Catalog > Layered Navigation i have options about Regular price.
How to setup same rules for Special Prices?
I activated Special Price Attribute in layered navigation form Attribute Manager in Admin but, in catalog list frontend, it shows with step fixed to 10!!! and no way to edit steps and/or ranges in backoffice!