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 $117.96   6.614%   $125.7619   $125.76   $125.75   $125.80  
  Purchase #2 $174.89   4.841%   $183.3564   $183.36   $183.35   $183.40  
  Purchase #3 $248.44   7.801%   $267.8208   $267.82   $267.80   $267.80  
  Purchase #4 $241.50   7.868%   $260.5012   $260.50   $260.50   $260.50  
  Purchase #5 $60.26   6.647%   $64.2655   $64.27   $64.25   $64.30  
  Purchase #6 $109.75   7.400%   $117.8715   $117.87   $117.85   $117.90  
  Purchase #7 $86.37   7.590%   $92.9255   $92.93   $92.95   $92.90  
  7 purchase totals = $1,039.17       $1,112.5028   $1,112.51   $1,112.45   $1,112.60