Cost Tiers for Purchasing

Are we able to set up cost tiers for POs (similar to how price tiers are able to be set up)? With many of our vendors, we get volume-based price breaks. I'd like to build those tiers into the system so I don't have to manually key in updates when we order at different tiers over time.

For example:

0-100 units @ $5 / unit

100+ units @ $4.75 / unit

500+ units @ $4.25 / unit

Etc.