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 $108.25   5.283%   $113.9688   $113.97   $113.95   $114.00  
  Purchase #2 $124.96   13.129%   $141.366   $141.37   $141.35   $141.40  
  Purchase #3 $44.64   5.111%   $46.9216   $46.92   $46.90   $46.90  
  Purchase #4 $84.35   3.235%   $87.0787   $87.08   $87.10   $87.10  
  Purchase #5 $136.52   12.779%   $153.9659   $153.97   $153.95   $154.00  
  Purchase #6 $54.97   12.794%   $62.0029   $62.00   $62.00   $62.00  
  Purchase #7 $209.55   5.475%   $221.0229   $221.02   $221.00   $221.00  
  7 purchase totals = $763.24       $826.3268   $826.33   $826.25   $826.40