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 $175.98   10.786%   $194.9612   $194.96   $194.95   $195.00  
  Purchase #2 $187.75   4.250%   $195.7294   $195.73   $195.75   $195.70  
  Purchase #3 $91.26   11.354%   $101.6217   $101.62   $101.60   $101.60  
  Purchase #4 $206.98   7.190%   $221.8619   $221.86   $221.85   $221.90  
  Purchase #5 $224.87   5.800%   $237.9125   $237.91   $237.90   $237.90  
  Purchase #6 $118.64   9.365%   $129.7506   $129.75   $129.75   $129.80  
  Purchase #7 $30.36   7.843%   $32.7411   $32.74   $32.75   $32.70  
  7 purchase totals = $1,035.84       $1,114.5784   $1,114.57   $1,114.55   $1,114.60