You need to use something like Microsoft Point of Service for .NET v1.12 (POS for .NET)
Microsoft Point of Service for .NET v1.12 (POS for .NET) is a class library that enables POS developers to apply Microsoft .NET technologies in their products. It provides a simple and consistent interface for .NET Framework applications to interact with POS devices, in compliance with the UnifiedPOS standard (aka UPOS). In addition, it provides windows plug and play (PnP) support. There are thirty-six classes of POS peripherals supported including cash drawer, receipt printer, barcode scanner, magnetic strip reader (MSR), line display, RFID, Biometric, Belt, Check Scanner, Fiscal Printer, Electronic Journal, Image Scanner, Item Dispenser, Magnetic Ink Character Recognition Reader (MICR), PIN Pad, signature capture device, etc. In addition, POS for .NET supports many legacy devices where OPOS service objects are available.
This is considered the preferred way to interact with POS devices from .Net.
You can also have a look at the UnifiedPOS page
In case you are using a Symbol scanner you can download the opos driver from
Microsoft Point of Service for .NET v1.12 is a set of .Net assemblies, all you need to do is to add a reference to the assembly.
OPOS is COM based, so you need to import the type library for the dll into .Net, which you can do in nearly the same manner you import .Net assemblies.
So both technologies are easily accessible from C# and .Net.