Any contact between humans is a possible vector for infection. If you have to handle money be careful not to touch your mouth or poke your nose. Use an antiseptic wipe or lotion on the hands frequently, and if you hear someone coughing open the window.
The period between Xmas week and 2nd week of January seems to be peak infection time for flu and colds. I'm sure the amount of frantic shopping during this period is a factor. It's the press of people rather than the money being passed that is the danger.