The cash register system does not receive any feedback from the cash register drawer when it is open or closed. Is this OK?

No, this does not comply with the regulations.

According to Section 2-6 fifth paragraph of the Cash Register System Regulation, it must not be possible to register sales in cash register systems if the integrated cash register drawer is open. If the cash register system does not have a block to prevent this, the system will have a function which is not permitted under the regulations. A function must therefore be incorporated into the program which notifies the cash register system when the cash register drawer is open.