Money handling

A payment method appears only after HyoNova has set up its payment provider.

A binary floating-point number never decides how much a customer pays. Every amount in HyoNova Commerce is an integer number of the currency's minor units together with its ISO 4217 currency code.

Representation#

Currency exponents#

Most currencies have 2 decimal places. HyoNova lists the exceptions explicitly:

A code that is not three capital letters is refused (CURRENCY_UNSUPPORTED).

Converting provider amounts#

Some providers send decimal amounts (FastSpring 14.95, Triple-A 10). HyoNova converts them with string arithmetic only:

• A JSON number is read through its shortest exact decimal form, never through its binary value.
• "14.95" USD → 1495; 1000 JPY → 1000.
• An amount with more decimals than the currency allows is refused, not rounded.
• Amounts sent to a provider are formatted from minor units the same way (1495 → "14.95").

Rounding#

• Percentages (discounts) are in basis points (2500 = 25%) and round half away from zero.
• Time-proportional amounts round half away from zero and are used only where policy says so; HyoNova never invents a provider charge. Proration of card plan changes is computed by the provider.
• Invoice totals always satisfy total = subtotal − discount + tax; the database enforces it, and that the amount paid never exceeds the total.

No currency conversion#

HyoNova never converts between currencies. Prices exist per currency, invoices and payments carry their own currency, a payment must match its invoice currency, and every revenue figure is reported per currency. A settlement fee the provider did not report stays unknown — it is never shown as zero.