Microsoft will update the price tier values for Windows Store during the week of April 13, 2015. Windows Store supports 96 tiers that publishers can use to price paid apps and in-app products. These price tier values are updated periodically to maintain consistency across currencies, accounting for changes in foreign exchange rates, taxes, and other geographic pricing considerations. The information comes through an email Microsoft has sent out to developers, alerting them of the change.

Beginning April 13, the price tier values will be updated and while the US Dollar (USD) price in each tier will remain the same, the prices in all other currencies adjusted relative to the USD price.
Read more: Get ready to pay more for apps on Windows Store from next month | Windows Central