giving a shop clerk money

Even after more that 7 months of being back in the states it is strange for me to take money out of my wallet and hand it to a person money with only one hand.  In China the proper way to give a person money or a business card is to hold it in both hands and present it, so to speak.  Any time I have to give some one money I still feel awkward just handing it to them.  There are many differences between China and the USA but this is the one that has given me the most trouble adjusting to now that I am back home.  Ok it is also hard to eat out and not pay 2 dollars for a meal.