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 $86.80   11.721%   $96.9738   $96.97   $96.95   $97.00  
  Purchase #2 $207.36   9.227%   $226.4931   $226.49   $226.50   $226.50  
  Purchase #3 $86.89   9.328%   $94.9951   $95.00   $95.00   $95.00  
  Purchase #4 $8.81   10.116%   $9.7012   $9.70   $9.70   $9.70  
  Purchase #5 $191.76   11.746%   $214.2841   $214.28   $214.30   $214.30  
  Purchase #6 $226.39   12.816%   $255.4041   $255.40   $255.40   $255.40  
  Purchase #7 $105.33   7.336%   $113.057   $113.06   $113.05   $113.10  
  7 purchase totals = $913.34       $1,010.9084   $1,010.90   $1,010.90   $1,011.00