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 $196.25   3.315%   $202.7557   $202.76   $202.75   $202.80  
  Purchase #2 $192.89   11.351%   $214.7849   $214.78   $214.80   $214.80  
  Purchase #3 $60.38   12.860%   $68.1449   $68.14   $68.15   $68.10  
  Purchase #4 $196.42   5.234%   $206.7006   $206.70   $206.70   $206.70  
  Purchase #5 $240.47   8.245%   $260.2968   $260.30   $260.30   $260.30  
  Purchase #6 $149.96   7.344%   $160.9731   $160.97   $160.95   $161.00  
  Purchase #7 $55.37   12.572%   $62.3311   $62.33   $62.35   $62.30  
  7 purchase totals = $1,091.74       $1,175.9871   $1,175.98   $1,176.00   $1,176.00