%% 
%%  A DANTE-Edition example
%% 
%%  Example 06-00-40 on page 205.
%% 
%%  Copyright (C) 2010 Herbert Voss
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%% 
%%  See http://www.latex-project.org/lppl.txt for details.
%% 
%% 
%% ==== 
% Show page(s) 1
%% 
\documentclass[]{article}
\pagestyle{empty}
\setlength\textwidth{375.57637pt}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}

\usepackage{tabularx,numprint,spreadtab}

\begin{document}
\nprounddigits2
\begin{spreadtab}{{tabularx}{0.8\linewidth}{|
  >{\rule[-1.2ex]{0pt}{4ex}}X >{{\bfseries}}N42
  >{\bfseries}c N42 >{\bfseries}c N42|}}\hline
@Pos. & @\multicolumn{1}{c}{price/unit} & @\multicolumn{1}{c}{number} &
@\multicolumn{1}{c}{price} & @\multicolumn{1}{c}{rebate} & @\textbf{net}\\\hline
@1 & 5.99 & 20 & [-2,0]*[-1,0] & $-:={20}\%$ & [-2,0]*(1-[-1,0]/100)\\
@2 & 12   & 7  & [-2,0]*[-1,0] & $-:={10}\%$ & [-2,0]*(1-[-1,0]/100)\\
@3 & 4.50 & 40 & [-2,0]*[-1,0] & $-:={35}\%$ & [-2,0]*(1-[-1,0]/100)\\
@4 & 650  & 2  & [-2,0]*[-1,0] & $-:={15}\%$ & [-2,0]*(1-[-1,0]/100)\\\hline
@\multicolumn{6}{c}{\vspace{-1.5ex}}\\\cline{4-6}
@\multicolumn{1}{c}{\rule[-1.2ex]{0pt}{4ex}} &
@\multicolumn{2}{r|}{sum} & sum(d2:[0,-2])
  & \multicolumn{1}{c}{$:={round(([1,0]/[-1,0]-1)*100,0)}\%$}
  & {\bfseries}:={sum(f2:[0,-2])}\\\cline{4-6}
@\multicolumn{3}{r|}{} & @\multicolumn{1}{r}{\textbf{VAT}} & @ 19\%
  & {\bfseries}:={[0,-1]*0.19}\\\cline{4-6}
@\multicolumn{3}{r|}{} &
@\multicolumn{2}{r}{\textbf{final sum}} & {\bfseries}:={[0,-2]+[0,-1]}\\\cline{4-6}
\end{spreadtab}
\end{document}