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 $91.70   3.723%   $95.114   $95.11   $95.10   $95.10  
  Purchase #2 $177.62   10.818%   $196.8349   $196.83   $196.85   $196.80  
  Purchase #3 $202.71   4.777%   $212.3935   $212.39   $212.40   $212.40  
  Purchase #4 $46.49   10.434%   $51.3408   $51.34   $51.35   $51.30  
  Purchase #5 $70.36   4.794%   $73.7331   $73.73   $73.75   $73.70  
  Purchase #6 $196.64   12.596%   $221.4088   $221.41   $221.40   $221.40  
  Purchase #7 $190.25   6.667%   $202.934   $202.93   $202.95   $202.90  
  7 purchase totals = $975.77       $1,053.7591   $1,053.74   $1,053.80   $1,053.60