Variance from a central limit approximation

Let $X_1,X_2,…,X_{100}$ be i.i.d. random variables with $E(X_1)=0$, $E(X_1^2)=\sigma^2$, where $\sigma>0$. Let $S=\sum_{i=1}^{100}X_i$. If an approximate value of $P(S\le30)$ is $0.9332$, then $\sigma^2$ equals __________________