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 $119.42   4.836%   $125.1952   $125.20   $125.20   $125.20  
  Purchase #2 $208.67   7.683%   $224.7021   $224.70   $224.70   $224.70  
  Purchase #3 $238.27   12.267%   $267.4986   $267.50   $267.50   $267.50  
  Purchase #4 $169.93   4.324%   $177.2778   $177.28   $177.30   $177.30  
  Purchase #5 $156.88   4.767%   $164.3585   $164.36   $164.35   $164.40  
  Purchase #6 $108.34   11.809%   $121.1339   $121.13   $121.15   $121.10  
  Purchase #7 $63.27   6.592%   $67.4408   $67.44   $67.45   $67.40  
  7 purchase totals = $1,064.78       $1,147.6069   $1,147.61   $1,147.65   $1,147.60