Round A4 up to a multiple of 4 total pages.

I can't easily get the number of actual pages processed, so rely
on telling the (rather hacky, and surprising - I have to
divide to a separate counter to force an integer result) macro
the number of pages used before the current numbering started.

docend.A4.tex

@@ -1,3 +1,4 @@
+\padpages{4}{8}
 \pagecolor{havocpurple}
 \thispagestyle{empty}
 \mbox{}

dottes.tex

@@ -1,11 +1,13 @@
 \input{docclass.tex}
 
 \usepackage{array}
+\usepackage{calc}
 \usepackage{caption}
 \usepackage{color}
 \usepackage{fontspec}
 \usepackage{graphicx}
 \usepackage{fancyhdr}
+\usepackage{ifthen}
 \usepackage[defaultlines=4,all]{nowidow}
 \usepackage{tabularx}
 \usepackage{longtable}
@@ -98,6 +100,28 @@
   \end{figure}
 }
 
+% Add blank pages to make total page count up to a multiple
+% Args are:
+%   1. Multiple desired
+%   2. Pages before start of current page count
+\newcounter{modpage}
+\newcounter{modpageno}
+\newcounter{modpagenodiv}
+\newcommand{\padpages}[2]{%
+    \pagestyle{empty}%
+    \setcounter{modpageno}{\thepage + #2}%
+    \setcounter{modpagenodiv}{\themodpageno/#1}%
+    \setcounter{modpage}{\themodpageno - #1*\themodpagenodiv}%
+    \ifthenelse{\themodpage=0}%
+        {\relax}%
+        {\setcounter{modpage}{#1 - \themodpage}%
+            \whiledo{\themodpage>0}{%
+                \mbox{}\clearpage\mbox{}%
+                \setcounter{modpage}{\themodpage - 1}%
+            }% end whiledo
+        }% end ifthenelse
+}% end padpages
+
 % ----- Paper size document setup
 
 \input{docsetup.tex}