One way to avoid the fatal pinch is the Dickens approach: Annual income twenty pounds, annual expenditure nineteen nineteen six, result happiness. Annual income twenty pounds, annual expenditure twenty pounds nought and six, result misery. In a world with AWS and pay-as-you go services, it's more and more possible.
(Zero sarcasm) can you possibly explain, in different words, what this means?
£19 19s 6d = £19.975
£20 0s 6d = £20.025