The indie, which has four stores in Wales, said the charge had gone "reasonably smoothly". "In the run-up to the law being introduced, we were concerned customers would be offended," said MD Paul Delves.
"But they seem to understand the rationale behind the move, especially when they realise proceeds are being donated to local charity Hope House."
During the past couple of weeks customers had either brought their own bags, purchased a Tuffins Bag for Life or paid the 5p charge, he added.
According to the Welsh government, in 2009/2010 Welsh shoppers took home 350 million carrier bags from major supermarkets or 273 bags per household.