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 $207.71   5.843%   $219.8465   $219.85   $219.85   $219.80  
  Purchase #2 $217.33   6.405%   $231.25   $231.25   $231.25   $231.30  
  Purchase #3 $70.59   3.762%   $73.2456   $73.25   $73.25   $73.20  
  Purchase #4 $188.50   7.341%   $202.3378   $202.34   $202.35   $202.30  
  Purchase #5 $60.66   9.644%   $66.5101   $66.51   $66.50   $66.50  
  Purchase #6 $176.93   12.634%   $199.2833   $199.28   $199.30   $199.30  
  Purchase #7 $63.37   6.612%   $67.56   $67.56   $67.55   $67.60  
  7 purchase totals = $985.09       $1,060.0333   $1,060.04   $1,060.05   $1,060.00