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 $181.84   7.764%   $195.9581   $195.96   $195.95   $196.00  
  Purchase #2 $207.37   7.147%   $222.1907   $222.19   $222.20   $222.20  
  Purchase #3 $197.49   11.541%   $220.2823   $220.28   $220.30   $220.30  
  Purchase #4 $43.76   10.553%   $48.378   $48.38   $48.40   $48.40  
  Purchase #5 $147.76   3.406%   $152.7927   $152.79   $152.80   $152.80  
  Purchase #6 $183.81   13.258%   $208.1795   $208.18   $208.20   $208.20  
  Purchase #7 $156.68   5.796%   $165.7612   $165.76   $165.75   $165.80  
  7 purchase totals = $1,118.71       $1,213.5425   $1,213.54   $1,213.60   $1,213.70