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 $114.38   3.772%   $118.6944   $118.69   $118.70   $118.70  
  Purchase #2 $185.92   5.419%   $195.995   $196.00   $196.00   $196.00  
  Purchase #3 $105.95   7.497%   $113.8931   $113.89   $113.90   $113.90  
  Purchase #4 $194.98   5.226%   $205.1697   $205.17   $205.15   $205.20  
  Purchase #5 $238.97   6.773%   $255.1554   $255.16   $255.15   $255.20  
  Purchase #6 $72.63   10.118%   $79.9787   $79.98   $80.00   $80.00  
  Purchase #7 $228.97   3.513%   $237.0137   $237.01   $237.00   $237.00  
  7 purchase totals = $1,141.80       $1,205.9000   $1,205.90   $1,205.90   $1,206.00