No approval needed on PO Workflow if the amount is less than spending limit

We have a PO workflow setup but I can’t seem to figure out how to automatically approve, or skip, the approval process if the PO amount is less than the submitter’s spending limit. It will always need an approval. It seems this is the very definition of what the spending limit should be used for but I must be missing something. Has anyone ran into this before or know how to remedy it? I’d prefer not to create custom code if it can be avoided.