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 $47.75   10.211%   $52.6258   $52.63   $52.65   $52.60  
  Purchase #2 $160.41   4.139%   $167.0494   $167.05   $167.05   $167.00  
  Purchase #3 $161.75   4.482%   $168.9996   $169.00   $169.00   $169.00  
  Purchase #4 $235.76   4.536%   $246.4541   $246.45   $246.45   $246.50  
  Purchase #5 $126.75   6.655%   $135.1852   $135.19   $135.20   $135.20  
  Purchase #6 $193.61   7.709%   $208.5354   $208.54   $208.55   $208.50  
  Purchase #7 $118.70   9.165%   $129.5789   $129.58   $129.60   $129.60  
  7 purchase totals = $1,044.73       $1,108.4284   $1,108.44   $1,108.50   $1,108.40