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 $181.35   7.549%   $195.0401   $195.04   $195.05   $195.00  
  Purchase #2 $97.50   8.424%   $105.7134   $105.71   $105.70   $105.70  
  Purchase #3 $180.26   3.455%   $186.488   $186.49   $186.50   $186.50  
  Purchase #4 $171.96   9.694%   $188.6298   $188.63   $188.65   $188.60  
  Purchase #5 $190.46   6.532%   $202.9008   $202.90   $202.90   $202.90  
  Purchase #6 $102.89   10.687%   $113.8859   $113.89   $113.90   $113.90  
  Purchase #7 $104.37   8.345%   $113.0797   $113.08   $113.10   $113.10  
  7 purchase totals = $1,028.79       $1,105.7377   $1,105.74   $1,105.80   $1,105.70