I went to Ikebukuro Biccamera today. The EF-S lens in the store is 120,200 Yen. 10% points and also up to 5000 Yen off another purchase at the same time.
10% points means if you have a point card that they will credit 10% of the money that you actually hand over on the point card. You can then use that credit towards another purchase. So if you pay them 120,200 Yen for the above lens they will put 12,020 points on the point card. Which is 12,020 yen off your next purchase. But if you used 20,000 points from the point card towards buying the lens then you would only hand over 100,200 Yen in cash and they would only put 10,020 points on your card. If you have more points on your card than the next item is worth then you don't hand over any cash. If you don't use the points eventually they expire (think it takes a year or two).
1 point = 1 Yen.
The 5,000 yen thing works a bit differently. Don't need a point card for that. You need to purchase another item at the same time, i.e. same transaction.. It needs to be of sufficently high value to get the full amount. Perhaps something like 20,000 Yen. I have only done this once so a bit hazy on all the details. Then you will get an immediate discount. If the second item isn't of sufficient value you will get less than 5,000 yen discount.
Yodobashi point system works the same as the Biccamera one. Don't think they have an equivalent to the 5,000 yen discount above.
Every item will have a point value, usually specificied just as a percentage. Usually 10% but could be up to 20%. Very few items have an added discount on another item.
Biccamera definitely doesn't allow using a point card and not paying the 5% consumption tax. It is one or the other but not both. You will always be better off using a point card if you can get one.
When comparing prices between B&H and Biccamera or Yodobashi you should take off the point value before converting the currency and also compare to the grey market price. So the EF-S 17-55 is worth 120,200 - 12,020 = 108, 180 yen ~ $USD937. And B&H price is $USD1179 so actually Biccamera is $240 cheaper and this ignores the 5,000 yen discount if you buy another item of sufficient value.
this is just to save you from doing the calculation in your head. No real significance.
It is a point system not a percentage discount on the second item. See the explanation above.
