[Solved] How to print a length accurately and with user-controlled rounding?

WillAdams Asks: How to print a length accurately and with user-controlled rounding?
Tried the printlen package, but it seems to not understand what 2.5in means:

Code:
documentclass{minimal} 
usepackage{printlen} 
uselengthunit{in} 
begin{document} 
newlength{advertwidth} 
setlength{advertwidth}{2.5in} 
printlength{advertwidth} 
end{document}

Typesetting the above yields 2.50049 in — is there something better?

NB – in addition to the above, the project in question needs the packages:

Code:
usepackage{calc,geometry,xcolor,graphicx,csvsimple}

the last in particular, conflicts w/ the answers initially provided.

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