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 $88.26   9.376%   $96.5353   $96.54   $96.55   $96.50  
  Purchase #2 $118.78   8.819%   $129.2552   $129.26   $129.25   $129.30  
  Purchase #3 $157.68   6.508%   $167.9418   $167.94   $167.95   $167.90  
  Purchase #4 $88.90   6.428%   $94.6145   $94.61   $94.60   $94.60  
  Purchase #5 $94.64   6.594%   $100.8806   $100.88   $100.90   $100.90  
  Purchase #6 $113.42   10.425%   $125.244   $125.24   $125.25   $125.20  
  Purchase #7 $16.59   10.144%   $18.2729   $18.27   $18.25   $18.30  
  7 purchase totals = $678.27       $732.7443   $732.74   $732.75   $732.70