Well after 2 days of playing with the shipping I figured a way out.

I just set the tare to;
0:0
and the table rate to;
1:0.00,2:5.50,3:11.00,4:16.50,5:22.00,6:27.50,7:33.00,8:38.50,9:44.00,10:49.50,1 1:55.00,12:60.50,13:66.00,14:71.50,15:77.00,16:82.50,17:88.00,18:93.50,19:99.00, 20:104.5

So I;m getting 5.50 per 454 grams, close to the 500. Good enough for me.

I decided to set the flat rate to 25.