Calculate compound interest given principal amount, annual interest rate, compounding frequency per year, and time in years. Use the compound interest formula: A = P(1 + r/n)^(nt) where A is the final amount, P is the principal, r is the annual rate (as a decimal), n is the compounding frequency, and t is the time in years.

Return the final amount rounded to 2 decimal places. If any input is null or invalid (negative values or zero compounding frequency), return null.

Examples:

Input: principal = 1000, annualRate = 0.05, compoundsPerYear = 12, years = 10 Output: 1647.01 Explanation: 1000 * (1 + 0.05/12)^(12*10) = 1647.01 Input: principal = 5000, annualRate = 0.08, compoundsPerYear = 4, years = 5 Output: 7429.74 Explanation: 5000 * (1 + 0.08/4)^(4*5) = 7429.74 Input: principal = -100, annualRate = 0.05, compoundsPerYear = 1, years = 5 Output: null Explanation: Negative principal is invalid
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