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 $61.26   8.760%   $66.6264   $66.63   $66.65   $66.60  
  Purchase #2 $211.64   11.357%   $235.676   $235.68   $235.70   $235.70  
  Purchase #3 $13.31   9.673%   $14.5975   $14.60   $14.60   $14.60  
  Purchase #4 $235.87   6.701%   $251.6756   $251.68   $251.70   $251.70  
  Purchase #5 $166.82   10.409%   $184.1843   $184.18   $184.20   $184.20  
  Purchase #6 $116.74   7.679%   $125.7045   $125.70   $125.70   $125.70  
  Purchase #7 $177.31   7.464%   $190.5444   $190.54   $190.55   $190.50  
  7 purchase totals = $982.95       $1,069.0087   $1,069.01   $1,069.10   $1,069.00