Japanese crash course for new translator: γη΄ζ: SOmething happens without fail, like it was promised to happen (considering the people involved or situation before the occurence) η¨θΎΌγΏ: While it's "Before tax", it actually means "Tax included" as in "before you pay off the tax come with your payment/salary". And when used on merchandises, it's the original meaning, Which is "your payment includes the tax for this merchandise".
Presumably, because she's overly genki/ditzy and wouldn't remember to take off the tag and would run to show the admiral as soon as she bought it.
That's quite cliche of her...Commander is staring at me...stareTax includedCommander, how do I look in this new outfit?Commander: Whoa! It suits you well, Fubuki.