Gross Calculations - MAC OS

we have 2 different csv files that we need to calculate daily sales by cross referencing Invoice numbers for method of payment(MOP). we need to know what the gross amount for each day is by type of payment method. For example. if we had 23 customers on jan 2. 2015, we need your app to tell us the total gross of all the invoices sorted by Cash, visa, master card, amex, A/R, Debit, etc. so if we have $1000 gross for jan. 2, it will break down by Method of Payment. we can get a data extract in CSV, HTM, TXT, and XML. the problem is all the detail is not in one database, so your software will need to take 2 CSV files and cross reference them and give us the data we are looking for each location. i have attached a few different combination of files. each zip file contains 2 csv files for cross reference. the app will need to be able to do the following: 1 - prompt user for the CSV files 2 - drop down to select "Store_Number" 3 - have a checklist for which days the user wants data from 4 - "CC Gross Sales" after days selected the following will be displayed a. Visa Gross Total b. MC Gross Total c. Amex Gross Total d. Debit Gross Total e. Discover Gross Total f. Shell Gross Total g. Wex Gross Total h. Gift Card Gross Total i. Synchrony Gross Total 5 - "CC Net Sales" will have net sales for each MOP above and a calculated total for each MOP. the formula is in the excel file attached "2013 Credit Card Report" 6 - "Fleets" different section of app to show individual Gross for the 3 MOP below and one row for total net of all 3 a. JLI National Fleet Gross Total b. Local Fleets Gross Total c. Sound Billing d. Total Fleet Net Sales 7 - "Sales Tax" will have total sales tax 8 - "Discounts & Promotions" will have total Discounts/Promotions i have attached 2 different sets of data for testing. can provide more Thank You!