fix(billing): show the cent Orb rounds up on per-metric charges

packages/billing/lib/clients/orb/adapters.ts

@@ -28,9 +28,9 @@ export function orbAmountToCents(amount: string | null | undefined): number | nu
 
     // Groups 2 and 3 are guaranteed by the pattern, but `noUncheckedIndexedAccess` can't see that.
     const whole = match[2] ?? '0';
-    // Some invoices carry more than two decimals; the extra digits are dropped, not rounded.
-    const fraction = match[3] ?? '';
-    const cents = Number(whole) * 100 + Number(fraction.padEnd(2, '0').slice(0, 2));
+    const fraction = (match[3] ?? '').padEnd(3, '0');
+    const roundsUp = Number(fraction[2]) >= 5;
+    const cents = Number(whole) * 100 + Number(fraction.slice(0, 2)) + (roundsUp ? 1 : 0);
     return match[1] === '-' ? -cents : cents;
 }
 

packages/billing/lib/clients/orb/adapters.unit.test.ts

@@ -281,13 +281,21 @@ describe('orbAmountToCents', () => {
         expect(orbAmountToCents('100')).toBe(10000);
     });
 
-    it('drops sub-cent precision rather than rounding up', () => {
+    it('rounds sub-cent precision half-up', () => {
+        // Orb's costs endpoint answers in full float precision. This is a real value from it.
+        expect(orbAmountToCents('0.01999999999999999872')).toBe(2);
         expect(orbAmountToCents('19.9900000000')).toBe(1999);
-        expect(orbAmountToCents('19.999')).toBe(1999);
+        expect(orbAmountToCents('19.994')).toBe(1999);
+        expect(orbAmountToCents('19.995')).toBe(2000);
         expect(orbAmountToCents('19.9')).toBe(1990);
         expect(orbAmountToCents('19.')).toBe(1900);
     });
 
+    it('carries the rounding into the whole part', () => {
+        expect(orbAmountToCents('0.999')).toBe(100);
+        expect(orbAmountToCents('1.999')).toBe(200);
+    });
+
     it('handles negative amounts', () => {
         expect(orbAmountToCents('-5.00')).toBe(-500);
     });