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 $191.25   7.491%   $205.5765   $205.58   $205.60   $205.60  
  Purchase #2 $88.26   7.588%   $94.9572   $94.96   $94.95   $95.00  
  Purchase #3 $38.84   9.313%   $42.4572   $42.46   $42.45   $42.50  
  Purchase #4 $76.96   3.456%   $79.6197   $79.62   $79.60   $79.60  
  Purchase #5 $59.71   7.501%   $64.1888   $64.19   $64.20   $64.20  
  Purchase #6 $184.66   6.660%   $196.9584   $196.96   $196.95   $197.00  
  Purchase #7 $171.40   11.574%   $191.2378   $191.24   $191.25   $191.20  
  7 purchase totals = $811.08       $874.9956   $875.01   $875.00   $875.10