A more common case than the 1k pennies I see is small item shops like convenience stores having a posted note for refusing to accept $50 and $100 bills. This seems totally fine per: https://www.treasury.gov/resource-center/faqs/Currency/Pages...

There is, however, no Federal statute mandating that a private business, a person or an organization must accept currency or coins as for payment for goods and/or services. Private businesses are free to develop their own policies on whether or not to accept cash unless there is a State law which says otherwise. For example, a bus line may prohibit payment of fares in pennies or dollar bills. In addition, movie theaters, convenience stores and gas stations may refuse to accept large denomination currency (usually notes above $20) as a matter of policy.

That's actually not what legal tender means: https://www.treasury.gov/resource-center/faqs/Currency/Pages...

Incorrect. You are not required to accept all and any form of legal tender. You do not have to count those pennies. You can refuse to accept that form of payment.

A sale is not a debt, so by the rules of the current system a shop can refuse to count those pennies.

https://www.federalreserve.gov/faqs/currency_12772.htm

True, but that's why I'm saying it doesn't sit right with me. I'm not debating what the law is. I'm saying, in my opinion, businesses should be allowed to refuse types of payments.

You can probably refuse any type of payment you want... except cash.

I believe in Canada they can and the limits are expressly stated.

You can refuse payment. But in doing so, you dissolve the debt.