\documentclass{minimal}
\usepackage{amsmath}
\usepackage[active,tightpage]{preview}
\setlength\PreviewBorder{1pt}
\usepackage{pgf}
\usepackage{tikz}
\usepgfmodule{plot}
\usepgflibrary{plothandlers}
\usetikzlibrary{shapes.geometric}
\usetikzlibrary{shadings}
\begin{document}
\begin{preview}
%tikz
\begin{tikzpicture}[every node/.style={draw,scale=1pt,minimum width=15pt,inner sep=3pt,line width=1pt,draw=black!20}]
\matrix[row sep=2pt,column sep=2pt]
{\node[fill=red]{1};&
\node[fill=red!50]{2};&
\node[fill=red!20]{3};&
\node[fill=red!80!green!50]{4};&
\node[fill=red!80!blue!60]{5};\\
};
\end{tikzpicture}
\end{preview}
\end{document}