Let \( x \) be the total number of free throws Hunter attempted. According to the problem, he misses 10% of his free throws. This means that the number of missed free throws can be represented as:
\[ 0.10x \]
We know from the problem statement that he missed 54 free throws. Thus, we can set up the equation:
\[ 0.10x = 54 \]
To solve for \( x \), we can divide both sides of the equation by 0.10:
\[ x = \frac{54}{0.10} \]
Calculating the right-hand side gives:
\[ x = 540 \]
Therefore, the total number of free throws Hunter attempted is
\[ \boxed{540}. \]