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 $62.26   10.128%   $68.5657   $68.57   $68.55   $68.60  
  Purchase #2 $62.33   11.381%   $69.4238   $69.42   $69.40   $69.40  
  Purchase #3 $205.88   5.386%   $216.9687   $216.97   $216.95   $217.00  
  Purchase #4 $25.81   6.616%   $27.5176   $27.52   $27.50   $27.50  
  Purchase #5 $237.48   4.664%   $248.5561   $248.56   $248.55   $248.60  
  Purchase #6 $194.59   9.144%   $212.3833   $212.38   $212.40   $212.40  
  Purchase #7 $242.51   9.471%   $265.4781   $265.48   $265.50   $265.50  
  7 purchase totals = $1,030.86       $1,108.8933   $1,108.90   $1,108.85   $1,109.00