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 $132.96   10.717%   $147.2093   $147.21   $147.20   $147.20  
  Purchase #2 $177.48   11.391%   $197.6967   $197.70   $197.70   $197.70  
  Purchase #3 $122.62   12.393%   $137.8163   $137.82   $137.80   $137.80  
  Purchase #4 $178.41   12.548%   $200.7969   $200.80   $200.80   $200.80  
  Purchase #5 $188.77   11.534%   $210.5427   $210.54   $210.55   $210.50  
  Purchase #6 $140.42   10.727%   $155.4829   $155.48   $155.50   $155.50  
  Purchase #7 $40.78   12.756%   $45.9819   $45.98   $46.00   $46.00  
  7 purchase totals = $981.44       $1,095.5267   $1,095.53   $1,095.55   $1,095.50