The command \cmidrule
has an optional argument in parenthesis where you can specify the side to be reduced.
Here is how your table can be achieved
\documentclass{article}
\usepackage{booktabs}
\begin{document}
\begin{tabular}{lrrr}
Age & Female & Male & Total \\
\midrule
Under 10 & 5 & 8 & 13 \\
10-30 & 57 & 61 & 118 \\
30-60 & 5 & 1 & 6 \\
Over 60 & 3 & 0 & 3 \\
\cmidrule(l){2-2}\cmidrule(l){3-3}\cmidrule(l){4-4}
TOTAL & 70 & 70 & 140 \\
\bottomrule
\end{tabular}
\end{document}

Here is another version with fixed columns and where the length of \cmidrule
is reduced by a fixed value:
\documentclass{article}
\usepackage{booktabs,array}
\newcolumntype{R}[1]{>{\raggedleft\arraybackslash}m{#1}}
\begin{document}
\begin{tabular}{l*{3}{R{1.2cm}}}
Age & Female & Male & Total \\
\midrule
Under 10 & 5 & 8 & 13 \\
10-30 & 57 & 61 & 118 \\
30-60 & 5 & 1 & 6 \\
Over 60 & 3 & 0 & 3 \\
\cmidrule(l{.7cm}){2-2}\cmidrule(l{.7cm}){3-3}\cmidrule(l{.7cm}){4-4}
TOTAL & 70 & 70 & 140 \\
\bottomrule
\end{tabular}
\end{document}
