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 $90.25   5.229%   $94.9692   $94.97   $94.95   $95.00  
  Purchase #2 $90.57   13.811%   $103.0786   $103.08   $103.10   $103.10  
  Purchase #3 $169.65   5.762%   $179.4252   $179.43   $179.45   $179.40  
  Purchase #4 $232.96   12.138%   $261.2367   $261.24   $261.25   $261.20  
  Purchase #5 $52.33   13.766%   $59.5337   $59.53   $59.55   $59.50  
  Purchase #6 $186.96   13.257%   $211.7453   $211.75   $211.75   $211.70  
  Purchase #7 $225.33   8.408%   $244.2757   $244.28   $244.30   $244.30  
  7 purchase totals = $1,048.05       $1,154.2644   $1,154.28   $1,154.35   $1,154.20