To start recording the voucher received from the customer, I suggest creating a Petty Cash account first. This is a convenient supply of cash so you can use it to pay small expenses.
Go to the Gear icon ⚙ and select Chart of Accounts.
Select the New button.
From the Account Type drop-down, choose Bank.
From the Detail Type drop-down▼, select Cash on hand.
Enter Petty Cash for the account name.
The opening balance will be created when you move money from the checking account by writing a check or transferring funds. If you already have money to use for petty cash, enter the amount in the Balance field, and choose the as of date.
Then, you'll have the options on how you can use or apply the remaining change of $40 with other transactions.
I'm also adding different articles to further guide you in effectively managing your business using QBO: Help guide for QuickBooks Online. It contains topics about advanced accounting, banking, and payments.
Don't hesitate to leave a comment below if you have any other questions. We're always here to help. Take care!