to answer the question..

what if the world only dealt with tonnes of gold
what if the world only dealt with 100 dollar bank notes
what if the world only dealt with barrels of oil
what if the world only dealt with whole bitcoins

.. well they dont

the world has grams, ounces of gold measure
the world has dollars and cents measures of fiat
the world has litres and gallons of oil measure
the world has bits and satoshi's of bitcoin measure.

so to answer your example
coffee = 12500 satoshi's          (1sat=0.00000001 bitcoin)
coffee = 125 bits                      (1bit=0.00000100 bitcoin)