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 $112.90   11.442%   $125.818   $125.82   $125.80   $125.80  
  Purchase #2 $225.63   4.449%   $235.6683   $235.67   $235.65   $235.70  
  Purchase #3 $72.99   12.632%   $82.2101   $82.21   $82.20   $82.20  
  Purchase #4 $162.36   8.523%   $176.1979   $176.20   $176.20   $176.20  
  Purchase #5 $132.38   9.680%   $145.1944   $145.19   $145.20   $145.20  
  Purchase #6 $161.51   10.571%   $178.5832   $178.58   $178.60   $178.60  
  Purchase #7 $146.49   11.198%   $162.894   $162.89   $162.90   $162.90  
  7 purchase totals = $1,014.26       $1,106.5659   $1,106.56   $1,106.55   $1,106.60