Sean,
There are many factors that will take place when assessing taxes. Mostly the price the you will be purchasing your home for. The City of Bloomington is responsible for estimating the market value of every property. They will make sure your assessment is equitable to other properties. The office carries past records of ownership, sale information, improvements and characteristics of a home. An analysis will be made of the current market conditions to estimate a market value and then an assessed value of your property.
If you are confussed yet, I would suggest checking out the Bloomington Normal property assessment website. http://www.wevaluebloomington.org/

Best Regards,
Gary Frost
Coldwell Banker Devonshire
309-477-7140

Sean, how they are figured and how you can figure them are 2 different ways. An easy shortcut is to figure about 2.2-2.4 % of the sales price per year. So a $100,000 home would be about $2,200-$2,400 /year and a $200,000 home would be about $4,400 to $4,800. The way the the County tax Assessors figure them is 1/3 of market value minis a homestead and/or senior discount times a multiplier for the city or area. My short cut comes out about the same most of the times.