ShopKeep POS Shopify

I was wondering if we could start a discussion about how people might use shopify on top of their own POS (Point of Sale) in store solution. A client of ours wants to add a shopping cart to their stores website. It is a boutique clothing store and will frequently be adding and removing items. Shopify seems perfect for this with its ease of use. However, the big worry is inventory and accounting integration. The store owner uses Quickbooks POS software and their merchant account is through quickbooks. ( i havn't been able to tell if Intuit resells merchant services for someone else? or if they have their own service). So far, my best suggestion to this client is to setup the Paypal Web Payments Pro service for use with shopify. This would probably be the cheapest and easiest right? Then for importing the information to be used by quickbooks for inventory and income, they can just import a CSV file directly from shopify. Does this suggestion seem to work? I do not have quickbooks so I do not know how well it handles the CSV files. I have come across a few forums posts about preparing the CSV files for quickbooks first but that is all I can find. Are there any other suggestions you guys might have for using other accounting systems? Thanks in advance for your help.

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ShopKeep POS Apple Pay