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 $33.41   4.801%   $35.014   $35.01   $35.00   $35.00  
  Purchase #2 $205.79   8.686%   $223.6649   $223.66   $223.65   $223.70  
  Purchase #3 $145.42   10.176%   $160.2179   $160.22   $160.20   $160.20  
  Purchase #4 $213.98   4.302%   $223.1854   $223.19   $223.20   $223.20  
  Purchase #5 $201.81   7.867%   $217.6864   $217.69   $217.70   $217.70  
  Purchase #6 $138.90   7.450%   $149.2481   $149.25   $149.25   $149.20  
  Purchase #7 $62.69   5.575%   $66.185   $66.19   $66.20   $66.20  
  7 purchase totals = $1,002.00       $1,075.2017   $1,075.21   $1,075.20   $1,075.20