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 $86.82   9.705%   $95.2459   $95.25   $95.25   $95.20  
  Purchase #2 $196.82   4.727%   $206.1237   $206.12   $206.10   $206.10  
  Purchase #3 $175.85   4.799%   $184.289   $184.29   $184.30   $184.30  
  Purchase #4 $107.44   11.803%   $120.1211   $120.12   $120.10   $120.10  
  Purchase #5 $81.99   3.553%   $84.9031   $84.90   $84.90   $84.90  
  Purchase #6 $10.41   12.352%   $11.6958   $11.70   $11.70   $11.70  
  Purchase #7 $53.96   3.667%   $55.9387   $55.94   $55.95   $55.90  
  7 purchase totals = $713.29       $758.3173   $758.32   $758.30   $758.20