بسم اللہ الرحمٰن الرحیم

:الجواب وباللہ التوفیق

Although you sell alcohol only by scanning it at the sales counter, even that, makes it a cursed and an illegal transaction, resulting in a job illegal to work at. 

The Messenger of Allah (Peace and Blessings of Allah be upon him) has cursed ten persons associated with alcohol. Among those are wine bearers, sellers, wine carriers, bartenders, and record keepers of alcohol are also included in the list. Therefore, it is necessary for you to find employment elsewhere. But if you are financially constrained at the time, you may continue until you find a halal source of income. In the meantime, keep repenting and seeking forgiveness from Allah (SWT) and donate in charity the income earned against the estimated time consumed during your sale of alcohol.

In Mishkaat al-Masabeeh:

وعن ابن عمر قال: قال رسول الله صلى الله عليه وسلم: «‌لعن ‌الله ‌الخمر وشاربها وساقيها وبائعها ومبتاعها وعاصرها ومعتصرها وحاملها والمحمولة إليه». رواه أبو داود وابن ماجه."

."كتاب البيوع، باب الكسب وطلب الحلال، ج: 2، ص: 846، ط: المكتب الإسلامي بيروت

Translation: 

It was narrated on the authority of Hazrat Abdullah Ibn Umar (RA) that the Messenger of Allah (Peace and Blessings of Allah be upon him) said: “That Allah the Exalted has cursed alcohol, the one who drinks it, the one who pours it (serves), the one who sells it, the one who buys it, the one who squeezes it (grapes etc.), the one for whom it is squeezed, the one who carries it, and the one to whom it is carried". 

فقط واللہ اعلم بالصواب