> 4.2% is what you need to stay even

On average, nationally. Look up your state or metropolitan-area CPI. Or better yet, track your actual expenses and project forward.

A conversation with your boss about a COLA raise really shouldn't include your own personal finances. "I just bought a house" is not a good reason for a raise; "prices in our area have increased" is a much better one

True, but how inflation affects each person is different. This isn't a good measure, but it is the best we have, and usually close enough to the truth.