sql decimal precision handling through vb.net

We are declaring one decimal precisison parameter as "Parameter1 decimal(10,2)"

In Stored Procedure to take any action on this variable we declared same as "@Parameter1 decimal(10,2)"

We used the Stored Procedure though our VB.Net source code as "_DBCmd.Parameters.Add("@Parameter1",SqlDbType.Decimal, 12).Value = Data to update"

Our query is while using the stored procedure should we declare SqlDbType.Decimal, 12 orSqlDbType.Decimal, 10?

Thanks..