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 $42.41   10.697%   $46.9466   $46.95   $46.95   $46.90  
  Purchase #2 $162.50   12.405%   $182.6581   $182.66   $182.65   $182.70  
  Purchase #3 $97.85   9.279%   $106.9295   $106.93   $106.95   $106.90  
  Purchase #4 $9.48   6.602%   $10.1059   $10.11   $10.10   $10.10  
  Purchase #5 $231.40   13.837%   $263.4188   $263.42   $263.40   $263.40  
  Purchase #6 $125.93   9.830%   $138.3089   $138.31   $138.30   $138.30  
  Purchase #7 $11.69   11.189%   $12.998   $13.00   $13.00   $13.00  
  7 purchase totals = $681.26       $761.3658   $761.38   $761.35   $761.30