Does there have to be a display facing the customer and what information does this display have to show?

No, there is no requirement for a separate display facing the customer at the point of sale.

Under current rules, amounts which are registered on a cash register must be clearly visible to the customer unless this is difficult to achieve; see Section 5-3-2 second sentence of the Bookkeeping Regulation. An example of a situation where this might be difficult to achieve is a restaurant where payment take place at ‘the tables’. According to Section 5-3-2a first paragraph, a receipt must always be printed out when the amount that is registered on the cash register is not clearly visible.

Neither the Cash Register System Act nor the Cash Register System Regulation contains a requirement for a cash register system to have a display. Instead, an absolute requirement has been introduced according to which it must not be possible to register sales without the system printing out a sales receipt; see Section 2-6 fourth paragraph of the Cash Register System Regulation. Therefore, the new regulations do not impose any requirements concerning the information which any display must show.