import module namespace
math="http://www.zorba-xquery.com/modules/math";

math:subtotal(11, (1345, 1301, 1368, 1322, 1310, 1370, 1318, 1350, 1303, 1299))


(:

Expected output:

<?xml version="1.0" encoding="UTF-8"?>
678.84


:)