You must keep records of all the purchases and sales your business makes. Your records must show that you properly collected, reported and forwarded taxes to Idaho.
Grocers can ask for relief from keeping detailed invoices of nontaxed sales by completing and mailing us 
Form ST-110 – Petition for Sales Tax Records Reduction By a Retail Food Store.
We’ll let you know if your request is approved and, if approved, how to use Form ST-111 – Sales Tax Records – Retail Food Stores in documenting your sales.
Records you must keep
- Normal books of account. (Books of account can include information stored on computers.)
- Documents that support entries in the books of account.
Examples:
- Bills
- Receipts
- Invoices
- Cash register tapes
- Job or work orders
- Contracts
- All schedules or working papers used to prepare your tax returns
- All records of sales (and credit granted for returned items).
- Purchases.
- Tax returns.
- Tax payments.
- Copies of sales tax resale or exemption certificates ( Form ST-101).
Note:
Keep a buyer’s exemption certificate for as long as you do business with that buyer, plus four years. We’ll bill you for tax due if you don’t have completed exemption certificates for buyers you sell exempt to.
What the records must show
- Gross receipts from sales and services made in Idaho, even sales that you or your customer might consider exempt from tax. If you deliver the product or service somewhere other than your place of business, you must also keep records that prove where delivery took place.
- The identity of customers claiming an exemption, the type of exemption, and what you sold them exempt.
- All deductions claimed in filing returns.
- The total purchase price of anything you bought for sale, rental, lease, or your own use.
- The amount of sales tax you collected from your customer, or that you paid to a vendor.
You must keep all sales and use tax records for four years. You should keep records for seven years if you don’t file returns.