Re: Pound Sterling
There are limits on some coins (less than £1) as to how much they are legal tender:
https://www.royalmint.com/help/trm-faqs/legal-tender-amounts/
has a list. No, you can't pay a £10,000 fine in 1p coins. But you could in £1 coins.
(The Mint claims these limits apply throughout the UK. Any Scottish law experts able to confirm or refute this?)