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 $59.33   5.650%   $62.6821   $62.68   $62.70   $62.70  
  Purchase #2 $225.42   3.720%   $233.8056   $233.81   $233.80   $233.80  
  Purchase #3 $227.43   6.866%   $243.0453   $243.05   $243.05   $243.00  
  Purchase #4 $236.71   3.768%   $245.6292   $245.63   $245.65   $245.60  
  Purchase #5 $144.85   3.565%   $150.0139   $150.01   $150.00   $150.00  
  Purchase #6 $148.70   3.159%   $153.3974   $153.40   $153.40   $153.40  
  Purchase #7 $33.45   8.787%   $36.3893   $36.39   $36.40   $36.40  
  7 purchase totals = $1,075.89       $1,124.9628   $1,124.97   $1,125.00   $1,124.90