How does TT determine land value? I entered $30k as the value of the land to determine the depreciable cost basis. Turbo Tax now says it's $30,279??

I'm looking for the calculation the TT does for determining the overall depreciable cost basis for a personal residence converted to a rental property. I entered purchase information, improvements costs, and land cost. TT now says my total is is MORE than the sum of all these things. How can this be?