Start from the selected merchandise base
One selected Cafiza jar at $19.99, Dezcal jar at $29.99 and Rinza bottle at $21.99 total $71.97 before charges. The tool parses decimal strings into integer cents before multiplication, addition or discount comparison. It accepts at most two fractional digits and rejects an extra fraction of a cent rather than silently rounding the input into another amount.
Allow an exact full-merchandise discount
A user-entered confirmed discount equal to $71.97 produces exactly $0.00 net merchandise for that basket. A $71.98 discount exceeds the base and is invalid. This rule addresses arithmetic equality; it does not assert that either seller offers such a promotion. An actual coupon can have additional restrictions, minimums or exclusions that the site does not validate.
Keep charge scope explicit
The discount applies to merchandise only in this tool. Shipping, tax and other actual charges are added when all are explicitly supplied. A full merchandise discount does not establish free delivery or zero tax, and this reference does not calculate tax law. Blank or invalid charge fields withhold a full total. Confirmed zeros are accepted as explicit user inputs, not inferred from a blank form.
Test meaningful boundaries
Local QA includes ten cents times three and two user-entered $47.99 units totaling $95.98 with an exact full discount. Those are labeled arithmetic test inputs, not fabricated current cleaner offers. Negative prices, scientific notation, fractional-cent amounts, invalid counts and discounts above a zero base are rejected. The maximum supported values remain within safe integer arithmetic for the three lines. No calculation reserves stock or approves a chemical-machine combination.
Zero is an explicit financial value
A blank shipping field is unknown, whereas an entered zero means the user has confirmed a zero charge for that calculation. A zero product quantity also creates zero merchandise without implying that a seller accepts a zero-unit order. The full-discount test only concerns the merchandise scope; positive actual delivery charges can remain payable. The tool does not compute those from a destination or recalculate tax rules after a discount. It accepts the user's actual quoted figures, rejects fractions of a cent and keeps the seller's commercial eligibility question outside the arithmetic.
Sources & scope
Checked November 4, 2026. Manufacturer and retailer references support the specific statements. Dated displayed prices are not final checkout quotes, performance rankings or performance testing. This shopping reference does not replace the exact product label or qualified individual advice. Current received labels, exact chemical/model authorization and independent chemical/equipment/content/commerce review remain pending.
Urnex US: Cafiza E31 12-E31-UX100 ↗
Keep reading
What do the three current cleaner offers actually include? ↗
How do 100 tablets and 12 jars change a Cafiza order? ↗
Can powder grams, liquid milliliters and tablets share one unit price? ↗