To generate test cases for the given problem statement, we need to create a function that will randomly select an integer \( N \) within the specified range (1 to 999) and derive the corresponding output based on the last digit of \( N \). Here is the test case generator function:

```python
import random

def determine_reading(N):
    last_digit = N % 10
    if last_digit in {2, 4, 5, 7, 9}:
        return f"{N}hon"
    elif last_digit in {0, 1, 6, 8}:
        return f"{N}pon"
    elif last_digit == 3:
        return f"{N}bon"

def tcgen():
    # Generate a random integer N within the range 1 to 999
    N = random.randint(1, 999)
    
    # Determine the correct reading based on the last digit of N
    result = determine_reading(N)
    
    return N, result

# Example usage
for _ in range(5):
    N, result = tcgen()
    print(f"Input: {N}")
    print(f"Output: {result}")
    print()
```

### Explanation:

1. **Function `determine_reading(N)`**:
    - This function takes an integer \( N \) and determines the reading based on the last digit of \( N \).
    - It uses modular arithmetic to extract the last digit of \( N \) and then checks which set the last digit belongs to (hon, pon, or bon).

2. **Function `tcgen()`**:
    - This function generates a random integer \( N \) within the range 1 to 999.
    - It calls `determine_reading(N)` to get the correct reading for \( N \).
    - It returns \( N \) and the corresponding reading as a tuple.

3. **Example usage**:
    - A loop is used to generate and print five sample test cases using the `tcgen()` function.

This generator ensures that all possible values of \( N \) within the constraints are tested, and it produces the correct expected output for each generated test case.