fix(pos): clamp payment amount to total + allow 1c tolerance for rounding

project/src/modules/pos/application/create-pos-sale.ts

@@ -111,7 +111,10 @@ export function validatePaymentAllocations(
     };
   });
   const allocatedCents = validated.reduce((sum, payment) => sum + payment.amountCents, 0);
-  if (allocatedCents > totalCents) {
+  // Allow up to 1 cent tolerance for rounding differences between the front-end
+  // POS calculation (which uses cached prices) and the back-end canonical total
+  // (which re-reads the catalogue under a transaction).
+  if (allocatedCents - totalCents > 1) {
     throw new AppError(
       400,
       'POS_PAYMENT_OVERPAYMENT',