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 $213.68   5.693%   $225.8448   $225.84   $225.85   $225.80  
  Purchase #2 $61.98   7.182%   $66.4314   $66.43   $66.45   $66.40  
  Purchase #3 $68.69   7.208%   $73.6412   $73.64   $73.65   $73.60  
  Purchase #4 $248.54   5.523%   $262.2669   $262.27   $262.25   $262.30  
  Purchase #5 $106.87   11.664%   $119.3353   $119.34   $119.35   $119.30  
  Purchase #6 $166.52   7.719%   $179.3737   $179.37   $179.35   $179.40  
  Purchase #7 $156.86   7.845%   $169.1657   $169.17   $169.15   $169.20  
  7 purchase totals = $1,023.14       $1,096.0590   $1,096.06   $1,096.05   $1,096.00