The currency selection in the settings of DT Register currently only apply to PayPal. To hard-code the component to use a different currency symbol than $, make the following changes in the dtregister.php found in:
/components/com_dtregister/
Wherever you find this code:
else
$currency_symbol=\'$\';
Change it to:
else
$currency_symbol=\'€\';
For an example, I just used € which will give the Euro currency symbol. Insert the symbol or the alt code for your symbol inside of the single quotes.
This is found on or around lines: 660, 1883, 1888, 3483, 3488, 5421, 7538, 9790, 11359, 12205, 13433, 14303, 15665, 15925, 16597, 17066, 18554, 19704, 20278, 20851, 21956, 22644, 23630, 24434, 24964
This solution will take care of your issue until we improve this in the next release.