In the name of Allah, the most Beneficent, the most Merciful.
Answer
It is narrated by Saaiduna Umar Bin Khattab Radiallahu Anhu that he said: “I heard the Prophet of Allah Sallallahu Alahi Wasalam say: “Actions are only according to intentions, and to each only what he intended. Whoever emigrates towards Allah and His Messenger, his emigration is towards God and His Messenger; whoever emigrates for the attainment of a worldly goal or in order to marry a woman, then his emigration is only towards what he emigrated to.” (Sahih Bukhari & Sahih Muslim)
Your intention was not to show the importance or significance of Christmas, hence, to
buy items on sale during the Christmas and Boxing Day sales will be permissible.
Only Allah Knows Best
Mohammed Tosir Miah
Darul Ifta Birmingham.
http://islamqa.org/hanafi/daruliftaa-birmingham/19460