Use integer pence
One selected offer of each totals£6.10 in merchandise. A confirmed merchandise-only credit of£6.10 leaves zero merchandise cost;£6.11 is rejected as one penny over the base. These are arithmetic checks,not a claim that any seller offers that credit or that the three references form one checkout.
Charges remain separate
With hypothetical delivery£4.99,additional tax£1.25 and other charges£0.00,a full merchandise credit still leaves£6.24. Those are tool inputs,not quoted merchant fees. Enter only genuinely additional tax and avoid adding included tax again.
Read the actual seller condition
Bart describes£4 postage below its£25 UK-mainland threshold and free delivery over£25,with3–5-day estimates. The exact£25 boundary and actual eligibility require checkout confirmation. That condition does not apply to Schwartz or Tesco. Do not buy extra stock solely on an assumed delivery entitlement.
Unknown is not zero
Blank shipping,tax or other charges withhold the final total. Money must be nonnegative,at most two decimals and within the stated bound;counts must be whole. The ledger also verifies10p×3=30p and£47.99×2=£95.98 without floating-point credit errors. No basket,health or personal information is sent externally.
A concrete purchase record
A delivered comparison can legitimately remain incomplete. If the maker jar price is known but its selected shipping fee is not,leave the fee blank. The calculator will show merchandise while withholding a final total. That outcome is more useful than forcing a zero charge simply to produce a convenient ranking across different sellers.
Sources & scope
Checked November 5, 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 retailer instructions. Current received labels and independent food-claim/content/commerce review remain pending.
Schwartz UK Ground Cumin37g maker record ↗
Bart Sweet Smoked Paprika40g maker record ↗
Tesco251505071 Old El Paso Smoky BBQ35g ↗