```typescript
function formatMicroUSD(microUnits: number): string {
  const microPerDollar = 1_000_000;
  const amountInUSD = microUnits / microPerDollar;

  // Round to two decimal places using half-up rule
  const roundedAmount = Math.round((amountInUSD + Number.EPSILON) * 100) / 100;
  
  return `$${roundedAmount.toFixed(2)}`;
}
```

This function converts micro-USD values to a formatted string with two decimal places, rounding half-up for precision.