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 $91.71   3.574%   $94.9877   $94.99   $95.00   $95.00  
  Purchase #2 $176.70   9.333%   $193.1914   $193.19   $193.20   $193.20  
  Purchase #3 $156.98   4.543%   $164.1116   $164.11   $164.10   $164.10  
  Purchase #4 $59.36   9.533%   $65.0188   $65.02   $65.00   $65.00  
  Purchase #5 $95.78   3.745%   $99.367   $99.37   $99.35   $99.40  
  Purchase #6 $175.72   6.874%   $187.799   $187.80   $187.80   $187.80  
  Purchase #7 $86.80   4.667%   $90.851   $90.85   $90.85   $90.90  
  7 purchase totals = $843.05       $895.3265   $895.33   $895.30   $895.40