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 $92.60   3.401%   $95.7493   $95.75   $95.75   $95.70  
  Purchase #2 $232.75   4.771%   $243.8545   $243.85   $243.85   $243.90  
  Purchase #3 $171.88   3.697%   $178.2344   $178.23   $178.25   $178.20  
  Purchase #4 $36.58   4.293%   $38.1504   $38.15   $38.15   $38.20  
  Purchase #5 $242.38   4.198%   $252.5551   $252.56   $252.55   $252.60  
  Purchase #6 $16.83   10.329%   $18.5684   $18.57   $18.55   $18.60  
  Purchase #7 $233.74   10.339%   $257.9064   $257.91   $257.90   $257.90  
  7 purchase totals = $1,026.76       $1,085.0185   $1,085.02   $1,085.00   $1,085.10