I was shopping at Big Bazaar

I was shopping at Big Bazaar and noticed a little old lady following me around. I stopped, she stopped.Furthermore she kept staring at me.
She finally overtook me at the checkout, and she turned to me and said, “I hope I haven’t made you feel ill at ease; it’s just that you look so much like my late son.”
I answered, “That’s okay.”
“I know it’s silly, but if you’d call out “Good bye, Mom” as I leave the store, it would make me feel so happy.”
She then went through the checkout, and as she was on her way out of the store, I called out, “Goodbye, Mom.”
The little old lady waved, and smiled back at me. Pleased that I had brought a little sunshine into someone’s day, I went to pay for my groceries.
“That comes to Rs. 6890/-” said the clerk. “How come so much . I only bought 5 small ticket items..”
The clerk replied, “Yeah, but your Mother said you’d be paying for her things too.”