Rate Not Holding Constant During Write Down in Bill Preparation

I am having a problem keeping the rate constant when writing down an Invoice.  What am I doing wrong

You probably are not doing anything wrong but you are suffering from the restrictions of “math.”  The Billed Billing Rate (the actual rate at which the time is billed), is a number that is calculated on the fly and is not saved anywhere in a data file.  Because it is a true mathematical equation (Bill Time x Bill Rate must always equal Bill Amount),  it is not always mathematically possible to keep the rate constant.  In these instances, you may have to play with individual transactions to get the bottom line number you want.  You may also want to consider using a Discount Style Invoice in this situation as all time, rates and amounts will be displayed on the Invoice at their original values.