```python
def step_rate(amount: int, fixed: int, percent: int) -> int:
    """Return the charge for one step:
    a fixed sum plus a whole-percent share of the amount,
    rounded down."""
    if amount <= fixed:
        return fixed
    else:
        return fixed + (amount * (percent / 100))

def rate_steps(amounts: list, fixed: int, percent: int) -> list:
    """Return the charge for each of several amounts, in order."""
    return [step_rate(amount, fixed, percent) for amount in amounts]
```