Question. The exchange rate was not added to your question. Below is the exchange rate used to answer this question. 
September 15 $ 0.60 
September 30 $0.66 
October 15 $0.62 
Answer: See the explanation for the prepared journal entry.
Step-by-step explanation:
Date Account title/Explanation Debit Credit
Sept 15 Account receivable (106,000*0.6) 63600
 Sales 63600
 (To record the sales)
Sept 30 Account receivable(106,000*(0.66-0.6) 6360 
 Foreign exchange gain 6360
 [ To record the adjustment of forex gain/loss]
Oct. 15 Foreign exchange gain/loss
 (106000*(0.66-0.62) 4240
 Account receivable 4240
 [ To record the entry for changes
 in the exchange rate]
Oct 15 Cash (106,000*0.62) 65720
 account receivable 65720
 [ To record the entry for receipt of payment]
Note; No journal entry require for 3rd entry.