\documentclass{article}
\usepackage{fp}
\usepackage[plain]{automultiplechoice}
\begin{document}

\newcommand{\testsection}[1]{\message{^^JSECTION(#1)^^J}}

\def\test#1#2#3{\AMCsignificantDigits{#1}{#2}\message{^^JTEST(\AMCshowSignificantDigits,#3)^^J}}

\testsection{Significant::base10}

\test{1.2345}{2}{12}

\test{0.034345}{2}{34}

\test{10789.5}{2}{11}

\test{-25678.56}{3}{-257}

\test{0.0065}{1}{6}

\test{-0.0065}{1}{-6}

\test{0.0075}{1}{8}

\test{-0.0075}{1}{-8}

\test{0.996}{2}{10}

\test{-9.76}{1}{-1}

\test{0}{3}{0}

\end{document}

