Retrieve Cell Values From A Datagridview?

I am trying to retrieve cell values from a datagridview.I am trying to use the DataGridView.Item().Value property to pull each cell value into a temp variable to it can be added up, but for some reason it is not accepting any variables that I use to count the rows, only integer values.Here is an example of the code I am using.

Dim tempVariable as Decimal
Dim i as Integer
Dim Total as Decimal

[code]....

For some reason it does not like the variable i, and only wants integer values.