If the three purchases and three sales that you described were your only transactions involving the "XYZ" ETF, then you do not have a wash sale. You report the three sales on your tax return, and claim all of the losses.
You didn't say what is complicated about the 1099-B from the broker. It should just show the three sales, with a loss on each one. But you said that the 1099-B shows a loss for "some" of the shares. The way you described the purchases and sales you have a loss on all of the shares. So there might be something you have not told us.
As for your rephrased example, if you buy an ETF for $100 and sell it 10 days later for $95, and you have no other purchases or sales of the same ETF, then you have a loss of $5, which you report on your tax return.
