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 $105.94   7.626%   $114.019   $114.02   $114.00   $114.00  
  Purchase #2 $55.93   7.544%   $60.1494   $60.15   $60.15   $60.10  
  Purchase #3 $240.81   7.331%   $258.4638   $258.46   $258.45   $258.50  
  Purchase #4 $221.74   11.114%   $246.3842   $246.38   $246.40   $246.40  
  Purchase #5 $160.46   3.641%   $166.3023   $166.30   $166.30   $166.30  
  Purchase #6 $92.54   7.873%   $99.8257   $99.83   $99.85   $99.80  
  Purchase #7 $71.99   7.534%   $77.4137   $77.41   $77.40   $77.40  
  7 purchase totals = $949.41       $1,022.5581   $1,022.55   $1,022.55   $1,022.50