Check out Hash Virtual Methods from the TT docs. Something like the following should work:

[% FOREACH shop IN vendor_sales.keys %]
<h1>[% shop %]</h1>
  [% FOREACH number IN vendor_sales.$shop.keys %]
  <h2>[% number %]</h2>
    <ul>
    [% FOREACH attr IN vendor_sales.$shop.$number.keys %]
      <li>[% attr %]: [% vendor_sales.$shop.$number.$attr %]</li>
    [% END %]
    </ul>
  [% END %]
[% END %]
[download]

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)