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 $167.26   4.801%   $175.2902   $175.29   $175.30   $175.30  
  Purchase #2 $106.92   11.672%   $119.3997   $119.40   $119.40   $119.40  
  Purchase #3 $207.76   6.701%   $221.682   $221.68   $221.70   $221.70  
  Purchase #4 $232.42   9.587%   $254.7021   $254.70   $254.70   $254.70  
  Purchase #5 $189.53   8.302%   $205.2648   $205.26   $205.25   $205.30  
  Purchase #6 $68.46   4.795%   $71.7427   $71.74   $71.75   $71.70  
  Purchase #7 $143.83   7.407%   $154.4835   $154.48   $154.50   $154.50  
  7 purchase totals = $1,116.18       $1,202.5650   $1,202.55   $1,202.60   $1,202.60