How about the voucher system?
Please note that it is NOT possible to pay in cash at the festival area!! Only official merchandise and non-food dealers and accepting cash! All others (food/beverage/ROA-Bar) are only accepting vouchers!
The cost of one voucher is 2,80 €. All prices are dividable by 2,80 €.
Unused vouchers can be exchanged back for cash at any time until the festival ends.