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 $42.44   10.149%   $46.7472   $46.75   $46.75   $46.70  
  Purchase #2 $226.66   5.138%   $238.3058   $238.31   $238.30   $238.30  
  Purchase #3 $93.96   3.130%   $96.9009   $96.90   $96.90   $96.90  
  Purchase #4 $190.69   8.475%   $206.851   $206.85   $206.85   $206.90  
  Purchase #5 $161.78   3.345%   $167.1915   $167.19   $167.20   $167.20  
  Purchase #6 $178.70   13.675%   $203.1372   $203.14   $203.15   $203.10  
  Purchase #7 $53.71   3.653%   $55.672   $55.67   $55.65   $55.70  
  7 purchase totals = $947.94       $1,014.8056   $1,014.81   $1,014.80   $1,014.80