The Japanese sales on vgchartz can be considered reliable since the site get them from either Famitsu or Media Create. The American sales on the other hand could be merely guesses. Here are the sales numbers and ranks in Japan from Famitsu:
Suikoden II sold 214,608 units in 1998 and was ranked at 62. In 1999, Suikoden II sold 159,711 more units for a total of 374,319 and was ranked at 98.http://geimin.net/da/db/1998_ne_fa/index.phphttp://geimin.net/da/db/1999_ne_fa/index.php
Suikoden III sold 377,729 units in 2002 and was ranked at 25.
Suikoden II book sold 42,471 units in 2002 and was ranked at 241.
Suikoden I book sold 33,167 units in 2002 and was ranked at 287.http://geimin.net/da/db/2002_ne_fa/index.php
Suikoden IV sold 300,437 units in 2004 and was ranked at 34.
Suikoden III the best sold 19,693 units in 2004 and was ranked at 441http://geimin.net/da/db/2004_ne_fa/index.php
Rhapsodia sold 64,472 in 2005 and was ranked at 197http://geimin.net/da/db/2005_ne_fa/index.php(Famitsu)
Suikoden V sold 194,780 units in 2006 and was ranked at 72
Suikoden I&II on PSP sold 28,271 units in 2006 and was ranked at 368http://geimin.net/da/db/2006_ne_fa/index.php(Media Create)
Suikoden V sold 183,653 units in 2006 and was ranked at 67 with first week sales of 135,289 units
Suikoden I&II on PSP sold 39,166 units in 2006 and was ranked at 279 with first week sales of 13,603 unitshttp://geimin.net/da/06/rank_mc.php
Unfortunately no sales for Suikoden I since the site I linked to does not have sales for the year 1995. I guess Suikoden I sold the majority of its copies on the first two weeks of its release and as a result the game did not show up on the listing for the year 1996. Suikoden I was release on December 15 of 1995 in Japan. No sales for Suikoden Tierkreis as well since it was released late on December of 2008 and could not make it to the list of best selling games.
Here are the sale numbers on vgchartz for those who are curious
Suikoden III 383,121
Suikoden II 381,708
Suikoden IV 304,561
Suikoden I 213,668
Suikoden V 191,673 ;_; I love this game
Suikoden Tierkreis 166,260
Suikoden I&II PSP port 26,884
Here is the url for those who are registered members on vgchartz:http://vgchartz.com/japtotals.php?name= ... &boxartz=1