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 $182.86   7.703%   $196.9457   $196.95   $196.95   $196.90  
  Purchase #2 $215.77   8.591%   $234.3068   $234.31   $234.30   $234.30  
  Purchase #3 $38.32   4.857%   $40.1812   $40.18   $40.20   $40.20  
  Purchase #4 $96.60   5.621%   $102.0299   $102.03   $102.05   $102.00  
  Purchase #5 $221.37   9.256%   $241.86   $241.86   $241.85   $241.90  
  Purchase #6 $114.38   7.137%   $122.5433   $122.54   $122.55   $122.50  
  Purchase #7 $209.50   11.171%   $232.9032   $232.90   $232.90   $232.90  
  7 purchase totals = $1,078.80       $1,170.7701   $1,170.77   $1,170.80   $1,170.70