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 $59.55   5.548%   $62.8538   $62.85   $62.85   $62.90  
  Purchase #2 $205.49   11.762%   $229.6597   $229.66   $229.65   $229.70  
  Purchase #3 $84.85   12.836%   $95.7413   $95.74   $95.75   $95.70  
  Purchase #4 $52.72   10.145%   $58.0684   $58.07   $58.05   $58.10  
  Purchase #5 $208.52   6.299%   $221.6547   $221.65   $221.65   $221.70  
  Purchase #6 $153.93   5.392%   $162.2299   $162.23   $162.25   $162.20  
  Purchase #7 $205.65   12.541%   $231.4406   $231.44   $231.45   $231.40  
  7 purchase totals = $970.71       $1,061.6484   $1,061.64   $1,061.65   $1,061.70