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 $119.35   5.355%   $125.7412   $125.74   $125.75   $125.70  
  Purchase #2 $171.67   4.157%   $178.8063   $178.81   $178.80   $178.80  
  Purchase #3 $104.97   12.497%   $118.0881   $118.09   $118.10   $118.10  
  Purchase #4 $55.64   7.405%   $59.7601   $59.76   $59.75   $59.80  
  Purchase #5 $161.34   11.485%   $179.8699   $179.87   $179.85   $179.90  
  Purchase #6 $202.73   4.117%   $211.0764   $211.08   $211.10   $211.10  
  Purchase #7 $133.44   12.727%   $150.4229   $150.42   $150.40   $150.40  
  7 purchase totals = $949.14       $1,023.7649   $1,023.77   $1,023.75   $1,023.80