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 $194.36   3.698%   $201.5474   $201.55   $201.55   $201.50  
  Purchase #2 $9.84   7.265%   $10.5549   $10.55   $10.55   $10.60  
  Purchase #3 $153.39   7.744%   $165.2685   $165.27   $165.25   $165.30  
  Purchase #4 $243.42   3.420%   $251.745   $251.75   $251.75   $251.70  
  Purchase #5 $138.57   4.256%   $144.4675   $144.47   $144.45   $144.50  
  Purchase #6 $75.79   11.646%   $84.6165   $84.62   $84.60   $84.60  
  Purchase #7 $195.92   11.189%   $217.8415   $217.84   $217.85   $217.80  
  7 purchase totals = $1,011.29       $1,076.0413   $1,076.05   $1,076.00   $1,076.00