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 $114.68   10.109%   $126.273   $126.27   $126.25   $126.30  
  Purchase #2 $189.43   8.648%   $205.8119   $205.81   $205.80   $205.80  
  Purchase #3 $196.57   6.431%   $209.2114   $209.21   $209.20   $209.20  
  Purchase #4 $149.53   8.417%   $162.1159   $162.12   $162.10   $162.10  
  Purchase #5 $64.83   5.165%   $68.1785   $68.18   $68.20   $68.20  
  Purchase #6 $225.81   5.747%   $238.7873   $238.79   $238.80   $238.80  
  Purchase #7 $127.91   11.147%   $142.1681   $142.17   $142.15   $142.20  
  7 purchase totals = $1,068.76       $1,152.5461   $1,152.55   $1,152.50   $1,152.60