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 $62.95   9.608%   $68.9982   $69.00   $69.00   $69.00  
  Purchase #2 $218.77   10.569%   $241.8918   $241.89   $241.90   $241.90  
  Purchase #3 $204.85   13.194%   $231.8779   $231.88   $231.90   $231.90  
  Purchase #4 $150.99   3.602%   $156.4287   $156.43   $156.45   $156.40  
  Purchase #5 $154.26   6.643%   $164.5075   $164.51   $164.50   $164.50  
  Purchase #6 $234.43   5.133%   $246.4633   $246.46   $246.45   $246.50  
  Purchase #7 $105.97   11.506%   $118.1629   $118.16   $118.15   $118.20  
  7 purchase totals = $1,132.22       $1,228.3303   $1,228.33   $1,228.35   $1,228.40