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 $174.79   11.638%   $195.1321   $195.13   $195.15   $195.10  
  Purchase #2 $175.82   11.840%   $196.6371   $196.64   $196.65   $196.60  
  Purchase #3 $201.36   8.179%   $217.8292   $217.83   $217.85   $217.80  
  Purchase #4 $223.36   4.621%   $233.6815   $233.68   $233.70   $233.70  
  Purchase #5 $52.96   12.403%   $59.5286   $59.53   $59.55   $59.50  
  Purchase #6 $136.36   9.776%   $149.6906   $149.69   $149.70   $149.70  
  Purchase #7 $48.42   6.462%   $51.5489   $51.55   $51.55   $51.50  
  7 purchase totals = $1,013.07       $1,104.0480   $1,104.05   $1,104.15   $1,103.90