In the times before there was electricity and before the invention of modern refrigeration techniques, salt was used in warm countries as a means of preserving fish, meat and vegetables. Salt was also important as an additive in food to compensate for salt deficiency due to high perspiration in warm regions.
Salt was fairly easy to obtain and could be found everywhere. Salt was valuable because it was used by many people. It was a highly marketable product and evolved into a means of payment. In Europe, the Romans paid their soldiers in salt. The Latin word for salt is 'sal'. The soldiers' pay was called 'salarium' from which our word salary is derived.
In Africa salt was also used as a means of payment. In Congo there was the dibanga or dibanda and in Ethiopia the Amolé or salt cake. The salt cake weighs about 100 to 900 gr and measures 20 to 25 cm.
Amolé struck us as an excellent name for a tax consultancy and administration office. And to answer the final question, unfortunately we only accept euros (or other common currencies).
Sources: NBB museum
Kurlansky Mark, Salt, A world History, New York, Walker and Company, 2002.