it will all be done at any Banco de Reservas office, yes.
the renewal license for 1 year is actually RD$5.045.- Pesos plus RD$805.-Pesos in case you have the carry license. if a gun permit for more than one year also a additional year's fee applies, so it would be exactly 2 times of the above mentioned fee. at least it is shoewn like that in the info-paper of the SEIP(secretaria de Interior y Policia) which i received a few days ago.
paying those fees/taxes make always 100% sure that all on the form is filled in correctly, those payments are not refundable, in case of an error on the form the fees would need to be paid again in full.
they are very strict on that.
Mike