Some info about Oricon policy (this was written in 2009):
Actual daily sales are collected from the POS System (Point-of-Sale System) of approx. 3,370 stores nationwide (this will be the projected sales you see on Oricon Daily)
by the end of the week, additional actual sales are also included from: i) another 700 stores that fax in their weekly sales results; ii) website sales; iii) sales from promotional events..etc.
Therefore, when the weekly sales figure is released, the total projected sales per Oricon Chart =/= total final sales
source: http://tokki.typepad.com/blog/2009/0...l-post-xd.html