First, if you donate a single item or a group of similar items with a value over $5000, you must have a qualified appraiser and you must submit a form 8332 signed by the appraiser. Splitting the donation up into smaller lots does not change the requirement.
Whether you donated $6000 of "used household items" and therefore 1 group over $5000, or different groups under $5000 ("used clothing", "furniture", "kitchen items" etc.) would probably be up to the discretion of the auditor if you are audited.
You must have qualified receipts from the charity. You must also have a list of items with sufficient detail (age, condition, description) to determine a fair market value. In the past, the IRS accepted drop-off receipts from places like Goodwill that said things like "2 bags", but we are hearing reports that auditors are getting more strict. The problem is that, even if you have a properly documented list of donated items, you don't have proof that those listed items were in those bags. It is better practice to have someone from the charity sign your list of items agreeing that you in fact donated the items on your list. (The charity will rarely agree to a value but they should sign to agree that you dropped off the items you said you did.)
You also need to take steps to verify that ITsDeductible values (if you use them) are reasonable for your part of the country. It'sDeductible values are generic nationwide values. You can get a list from the thrift shop of what they actually typically charge, or go into the store and check the price tags to confirm that the its deductible values are reasonable fair market values for your area.
If you claim 10 donations from goodwill, each less than $5000 but with a combined value more than $5000, you will be at increased risk of audit. Be aware of the rules and concerns mentioned and be prepared.
