

Pennies only have to be accepted if there is a state law saying so. For example in California if a landlord refuses a cash payment (pennies or otherwise) then the tenant basically gets free rent that month. Businesses generally set their own rules as to what is accepted. Just like you see signs saying “No bills over $20” - 50’s and 100’s are legal tender, but they can refuse them just like a bucket of pennies can be refused.
Since you feel like quoting things is conducive to proper discusion:
https://www.federalreserve.gov/faqs/currency_12772.htm