Keep in mind some Danish businesses will either charge extra for using a credit card (3 to 5% usually) or give a discount for cash - we saw this detail on the menu of 7 or 8 different restaurants in Copenhagen, and in a couple independent shops. Depending on your bank's fees, it might be worthwhile to get $75 from an ATM in Danish currency - buses, Tivoli, meals could easily total that for a day.