① I'm just looking.
Pronunciation: Chotto miru dake dess. (lit. "I just look a little")
Japanese: ちょっと見るだけです。

Retail staff in Japan will often come right up to you when you enter. Use this phrase if you'd like some time to yourself first.

② How much is this?
Pronunciation: Kore wa ikura dess-ka?
Japanese: これはいくらですか？

③ Where are the sale items?
Pronunciation: Seh-ru shoh-hin wa doko ni arimass-ka?
Japanese: セール商品はどこにありますか？

④ Can you make this duty-free here?
Pronunciation: Koko wa menzei ni dekimass-ka?
Japanese: ここは免税にできますか？

Japan has an increasing number of duty-free shops, but if you're in a larger store, it may depend on the counter you go to. Check before you buy!

⑤ I'd like this, please.
Pronunciation: Kore wo kuda-sai.
Japanese: これをください。

This is how you can let retail staff know when you've decided what you'd like to purchase.

⑥ I'd like a receipt, please.
Pronunciation: Reshiito wo kuda-sai.
Japanese: レシートをください。

You'll usually get a receipt automatically, but just in case. It's always good to keep the receipt just in case you discover a problem with your purchase later.

⑦ What's the best-before date?
Pronunciation: Shomi kigen wa itsu made dess-ka?
(lit. "Until when is the best-before period?")
Japanese: 賞味期限はいつまでですか？

When buying fruit or snacks as a gift for people back home, it's best to check the shelf life. This will often be stamped on the outside of the package as well.

⑧ Can I try it on?
Pronunciation: Shi-chaku dekimass-ka?
Japanese: 試着できますか？

It's always best to make sure you've got the right size—sizes in Japan may not be what you're used to!

⑨ Is this made in Japan?
Pronunciation: Kore wa nihon-sei dess-ka?
Japanese: これは日本製ですか？

If you've gone to the trouble of coming all the way to Japan, you may want to make sure you're buying something actually locally made.

⑩ Are there English instructions?
Pronunciation: Eigo no setsumei-sho wa arimass-ka?
Japanese: 英語の説明書はありますか？

If you're buying an electrical appliance, this could be more than a little important!

That's a start! And if there's anything else you need, gestures go a long way. And if you want to learn some more helpful Japanese phrases, take a look here!