Answer
False.
$(5°)^2=25 (°)^2$, that is $25~deg^2$. It is the measure of a solid angle (Do a search about solid angles). So it makes no sense to evaluate $tan(25~deg^2)$
Work Step by Step
But, assume that $tan[(5°)^2]=tan~25°$. We have that:
$tan[(5°)^2]=tan~25°\approx0.466\ne(tan~5°)^2\approx0.00765$
