Mandaloun Resto Lounge Inc

I brought my employees for Christmas party to that restaurant. The food was nice, and we had a good time. I paid the bill for the company, but I did not add a tip. I left earlier and my co-workers stayed longer. I had a feeling that the party went well, but the next day I noticed pretty sour faces of my co-workers. It turned out, after I had left, they were approached by the restaurant's staff and they were told that because their boss did not pay any tip, my co-workers HAD to pay tips! I reimbursed my co-workers on the following day for the tips that they paid at the restaurant, but the holiday atmosphere was ruined.My question is: did I HAVE to leave a tip?! I am left with a feeling that the restaurant's staff does not care about its customers, and I find it unacceptable to approach customers and to demand a tip. On that reason, I do not recommend the restaurant.