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 $59.25   5.819%   $62.6978   $62.70   $62.70   $62.70  
  Purchase #2 $70.34   5.339%   $74.0955   $74.10   $74.10   $74.10  
  Purchase #3 $222.61   8.633%   $241.8279   $241.83   $241.85   $241.80  
  Purchase #4 $105.94   4.516%   $110.7243   $110.72   $110.70   $110.70  
  Purchase #5 $218.60   11.605%   $243.9685   $243.97   $243.95   $244.00  
  Purchase #6 $145.84   3.116%   $150.3844   $150.38   $150.40   $150.40  
  Purchase #7 $250.38   4.202%   $260.901   $260.90   $260.90   $260.90  
  7 purchase totals = $1,072.96       $1,144.5994   $1,144.60   $1,144.60   $1,144.60