How to insert curly bracket in multirow table

The bigdelimpackage, which comes with multirow is designed for this sort of things. I added some improvements of the table with makecell and booktabs:

\documentclass[11pt]{report}
\usepackage{textcomp}
\usepackage{amsmath}
\usepackage{array, multirow, bigdelim, makecell, booktabs} 

\begin{document}

\begin{center}
\renewcommand{\theadfont}{\normalsize\bfseries}
\begin{tabular}{c c cl}
\thead{Cycle\\ Step} & \thead{Temp \\(\textcelsius)} & \thead{Time}\\
\cmidrule{1-3}
1 & 95 & 5\,min \\
2 & 95 & 30\,s & \hspace{-1em}\rdelim\}{3}{*}[${}\times35$ cycles] \\
3 & 60 & 30\,s \\
4 & 68 & 40\,s \\
5 & 68 & 5\,min \\
\end{tabular}
\end{center}

\end{document} 

Something like that?

Addendum

Another solution to let the right brace out of the tabular, with an ugly hack, to mimic what @Bernard proposed.

\documentclass[11pt]{report} 
\usepackage{amsmath}
\usepackage{multirow}
\usepackage{array}
\usepackage{siunitx}
\usepackage{booktabs}


\begin{document}

    \begin{center}
        \begin{tabular}{@{}c c l@{}}
            \toprule
            \textbf{Cycle Step} & \textbf{Temp $\left(\si{\celsius}\right)$} & \textbf{Time}\\
            \midrule
            1 & 95 & \SI{5}{\minute} \\
            2 & 95 & \multirow{3}{*}{$\left.\begin{array}{l}
                \SI{30}{\second}\\
                \SI{30}{\second}\\
                \SI{45}{\second}
                \end{array}\right\rbrace\times\SI{35}{cycles}$} \\
            3 & 60 &  \\
            4 & 68 & \\
            5 & 68 & \SI{5}{\minute}\\
            \bottomrule
        \end{tabular}

        \begin{tabular}{@{}c cc@{} l@{}}
            \cmidrule{1-3}
            \textbf{Cycle Step} & \textbf{Temp $\left(\si{\celsius}\right)$} & \textbf{Time}\\
            \cmidrule{1-3}
            1 & 95 & \SI{5}{\minute} & \\
            2 & 95 & \SI{30}{\second} & \multirow{3}{*}{\hspace{-1em}$\left.\begin{array}{l}
                \\
                \\
                \\
                \end{array}\right\rbrace\times\SI{35}{cycles}$} \\
            3 & 60 & \SI{30}{\second} & \\
            4 & 68 & \SI{45}{\second} &\\
            5 & 68 & \SI{5}{\minute}\\
            \cmidrule{1-3}
        \end{tabular}
    \end{center}

\end{document}