Printing POS from a webform

I have a pos system done in asp.net webform using C# that is already running since January 2020. There is just a little and minor issue when printing the pos receipt. By the way, my POS machine printer is made from China. Below are images to further explain the little issue that I raised above:

 

1. The report viewer is displayed

 

2. When you click the Print, it will open a print dialog box 

 

 

I've already searched for months now on how to print this receipt programmatically but I failed to find an answer. If someone out there can show me or teach me how to print my receipt programmatically, I will really appreciate it. Below is my code when printing the receipt.