Hi Hadi,
It is because StocksCafe is using averaging and not LIFO methodology in computing average price -> Calculation method for CLOSED
Also, for Day 3, I checked, your buy price was 0.54 instead of 0.94. Likewise the sell price was 0.52 instead of 0.92.
Day 1: Bought 5000 shares @ 0.945 => Total Shares 5K, Total Cost = 4725, Price per share = 0.945
Day 2: Bought 5000 shares @ 0.925 => Total Shares 10K, Total Cost = 9350, Price per share = 0.935
Day 3: Bought 10000 shares @ 0.54 => Total Shares 20K, Total Cost = 14750, Price per share = 0.7375
When you sell at Day 3, it does not affect the average price. so, average price is 0.7375 ~= 0.744 (StocksCafe actually also factor in fees which we skipped here for simplicity).
Cheers,
Evan