Credit cards are accepted in all larger stores and in about 60% of the mom & pop shops you´ll find along the way.
Argentine pesos are accepted everywhere and more and more, vendors are now accepting US Dollars. The advantage of paying in US Dollars is that the stores will often give you an exchange rate that is more favorable when compared to the official exchange rate. Having said that, you should always have a plan B when purchasing items in case they won’t accept US dollars (ie, local currency or Credit Card)
Argentina charges a Value Added Tax (VAT) on all goods and services purchased in the country. The rate is 21% (except for transporation which is 10.5%) and all displayed prices will have already have the VAT tax included. You will not need to add tax to any displayed amounts for goods and services.