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 $119.40   4.849%   $125.1897   $125.19   $125.20   $125.20  
  Purchase #2 $221.83   6.812%   $236.9411   $236.94   $236.95   $236.90  
  Purchase #3 $187.84   12.339%   $211.0176   $211.02   $211.00   $211.00  
  Purchase #4 $209.35   13.108%   $236.7916   $236.79   $236.80   $236.80  
  Purchase #5 $156.33   5.645%   $165.1548   $165.15   $165.15   $165.20  
  Purchase #6 $222.84   4.846%   $233.6388   $233.64   $233.65   $233.60  
  Purchase #7 $248.50   5.813%   $262.9453   $262.95   $262.95   $262.90  
  7 purchase totals = $1,366.09       $1,471.6789   $1,471.68   $1,471.70   $1,471.60