Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
  Case Tag  
Price  
Sales  
Tax %  
Raw Total  
Incl. Sales Tax  
Rounded  
to Penny  
Rounded  
to Nickel  
Rounded  
to Dime  
  Purchase #1 $207.62   7.263%   $222.6994   $222.70   $222.70   $222.70  
  Purchase #2 $164.95   5.644%   $174.2598   $174.26   $174.25   $174.30  
  Purchase #3 $67.69   8.852%   $73.6819   $73.68   $73.70   $73.70  
  Purchase #4 $67.30   7.292%   $72.2075   $72.21   $72.20   $72.20  
  Purchase #5 $195.83   11.644%   $218.6324   $218.63   $218.65   $218.60  
  Purchase #6 $238.57   6.785%   $254.757   $254.76   $254.75   $254.80  
  Purchase #7 $234.29   4.178%   $244.0786   $244.08   $244.10   $244.10  
  7 purchase totals = $1,176.25       $1,260.3166   $1,260.32   $1,260.35   $1,260.40