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 $196.89   7.119%   $210.9066   $210.91   $210.90   $210.90  
  Purchase #2 $24.37   8.565%   $26.4573   $26.46   $26.45   $26.50  
  Purchase #3 $33.38   10.767%   $36.974   $36.97   $36.95   $37.00  
  Purchase #4 $80.55   9.327%   $88.0629   $88.06   $88.05   $88.10  
  Purchase #5 $83.94   13.172%   $94.9966   $95.00   $95.00   $95.00  
  Purchase #6 $185.79   11.723%   $207.5702   $207.57   $207.55   $207.60  
  Purchase #7 $190.34   5.525%   $200.8563   $200.86   $200.85   $200.90  
  7 purchase totals = $795.26       $865.8239   $865.83   $865.75   $866.00