Hi everyone, thanks for the responses... it always surprises me, the breadth of knowledge we have at this forum. I did a little researching and I found some pretty interesting info regarding some of my questions.
First, it seems I do not need to charge sales tax on most of my boxes, irrespective of the food vs. non-food items. This is because Washington is as destination-based sales tax rate (as opposed to a origin-based sales tax state). This means that even though most of my customers are Washington residents and use a Washington billing address, since the destination for my box is almost always out of my state (Washington is my only Nexus) the I do not need to charge tax since the transaction is considered to take place where the box is delivered. Here's some good reading on the matter:
https://blog.taxjar.com/use-billing-address-shipping-address-calculating-sales-tax/https://taxify.co/2015/08/19/origin-vs-destination-based-sales-tax/^this one is interesting since it actually uses WA in the example
Second, I have discovered that my product is considered a "combined" sale according to this page:
http://apps.leg.wa.gov/wac/default.aspx?cite=458-20-244Where it gives a really interesting example:
"(5) How are combined sales of taxable and exempt items taxed?
(a) Combined sales. Where two or more distinct and identifiable items of tangible personal property, at least one of which is a food or food ingredient, are sold for one nonitemized price that does not vary based on the selection by the purchaser of items included in the transaction:
• The entire transaction is taxable if the seller's purchase price or sales price of the taxable items is greater than fifty percent of the combined purchase price or sales price; and
• The entire transaction is exempt from retail sales tax if the seller's purchase price or sales price of the taxable items is fifty percent or less of the combined purchase price or sales price.
The seller may make the determination based on either purchase price or sales price, but may not use a combination of the purchase price and sales price.
(b) Example.
A combination wine and cheese picnic basket contains four items packaged together: A bottle of wine, a wine opener, single-serving cheeses, and the picnic basket holding these items. The seller's purchase price for the wine, wine-opener, and picnic basket totals ten dollars. The seller's purchase price for the cheeses is two dollars. The seller must collect retail sales taxes on the entire package, because the seller's purchase price for the taxable items (ten dollars) is greater than fifty percent of the combined purchase price (twelve dollars)."
So it seems that as long as the non-taxable items in each box are valued at more than 50% the total box items value, then the entire box is not subject to sales tax. This will be very valuable to me if I decide to do a "valentines" box next year in which I will probably see boxes purchased by Washington residents and delivered to Washington residents.
Thoughts?