well, we know the aquarium is 23 bucks, the total is 23.23 or namely the tax is 0.23.
if we take 23 to be the 100%, whas is 0.23 off of it in percentage?
[tex]\begin{array}{ccll} amount&\%\\ \cline{1-2} 23&100\\ 0.23&x \end{array}\implies \cfrac{23}{0.23}=\cfrac{100}{x}\implies 23x=23\implies x=\cfrac{23}{23}\implies x=\stackrel{\%}{1}[/tex]
