Retail applications has majorly fraud prevention, procurement, shipping and tax related, pricing, real time bank authentication applications integrated to make the application run successfully. Integration testing here plays an important role as it requires that all applications interact with each other and also interact correctly so that Retailer is at benefit. Different testing techniques and types are used to test the application. Different testing teams will perform integration testing but what is the correct approach and how should you proceed is the major concern of many. Here we propose at what stage of Software Testing Life Cycle (STLC), integration testing should be initiated. Also what should be the approach of performing the testing? An example on Online Retail Application is used to understand the approach.