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 $191.81   5.302%   $201.9798   $201.98   $202.00   $202.00  
  Purchase #2 $61.56   3.124%   $63.4831   $63.48   $63.50   $63.50  
  Purchase #3 $168.89   12.345%   $189.7395   $189.74   $189.75   $189.70  
  Purchase #4 $169.42   9.500%   $185.5149   $185.51   $185.50   $185.50  
  Purchase #5 $166.61   6.872%   $178.0594   $178.06   $178.05   $178.10  
  Purchase #6 $205.87   13.827%   $234.3356   $234.34   $234.35   $234.30  
  Purchase #7 $127.76   11.470%   $142.4141   $142.41   $142.40   $142.40  
  7 purchase totals = $1,091.92       $1,195.5264   $1,195.52   $1,195.55   $1,195.50