Why You Should Never Use Floating Point for Money

Floating-point types like float and double are unsuitable for financial calculations due to inherent rounding errors. The recommended approach is to use BigDecimal with explicit scale and HALF_EVEN (Bankers') rounding mode. Financial logic should be encapsulated in an immutable Price Value Object to ensure consistent rounding and currency validation across the application. A robust test suite must cover edge cases like penny gaps from division, rounding boundaries, and extreme decimal scales.