Big Bazaar - Charged taxes twice

I Recently Purchased Goods For Total Of Rs **** From Bigbazaar And Included In This Purchase Was Few Shirts Tees Leggie And A Kurta And While Purchasing This The Banner Of The Counter Said ** Percent Off. Tags On All The Clothes Said Incl. Of All Taxes And Thus When Tax Are Included In The Price As Per The Tags Then The Discounts Of **% As Shown On The Counter Should Also Include The Taxes However I Was Charged Gst On Top Of The Prices After **%. No Where On The Counter It Was Mentioned That Gst Will Be Charged On The Top Of The Prices. Further The Gst Has Been Charged As *.* Cgst And *.* Sgst On All Items Whether The Price Was *** Or *** So Just Wanted To Know What Does Tag Means When It Says Incl. Of All Taxes And Gst Is Still Charged On Top Of That, Is It Not Double Taxation And Cheating Practices That Harm Not Only Individuals But Nation As A Whole? Its Not Matter Of ** Rs And Actually I Donot Really Want Them But Wanted To Know If In Fact The Taxes You Say Are Included In The Prices On One Side And Are Charged On The Bills On The Other Side Are Justified Or Not?