Consumption tax, similar to VAT in Europe went up to 10% on 01 October 2019. Till 30 September was 8%. However, foods and beverage excluding alcohols sold at supermarkets will remain as 8%. Then, if you eat inside the fast food restaurant it will be 10% but if it is take out, it will be 8%.
Therefore if you buy a sandwich, a coke and an umbrella at convenience store in Tokyo, sandwich and coke will be added 8% but the umbrella will be added 10%.
Also the prices are usually not including the consumption tax therefore if the price of the sandwich shows JPY 200, you have to pay JPY 216 at the cashier. JPY 250 beer will be JPY 275.
Consumption tax was introduced on 01 April 1989, at that time it was just 3%. Then, the government raised the tax to 5% on 01 April 1997, then to 8% on 01 April 2014. Anyway the consumption tax in Japan is still lower than the European standard.