The WooCommerce Pricing & Discounts! plugin (WCTBP) is a powerful tool that allows the shop admin to create price and discount rules that dynamically set products price, cart discounts or adds fees to cart according to time periods, quantity (currently in cart or item stock value left), amounts spent (per items or cart total) and user roles (for automatic role assignment give a look to companion plugin: WooCommerce Role by Amount Spent).
v14.6