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 $66.83   4.662%   $69.9456   $69.95   $69.95   $69.90  
  Purchase #2 $106.61   12.294%   $119.7166   $119.72   $119.70   $119.70  
  Purchase #3 $147.70   10.518%   $163.2351   $163.24   $163.25   $163.20  
  Purchase #4 $145.49   4.297%   $151.7417   $151.74   $151.75   $151.70  
  Purchase #5 $160.77   11.696%   $179.5737   $179.57   $179.55   $179.60  
  Purchase #6 $196.98   4.759%   $206.3543   $206.35   $206.35   $206.40  
  Purchase #7 $57.55   4.425%   $60.0966   $60.10   $60.10   $60.10  
  7 purchase totals = $881.93       $950.6636   $950.67   $950.65   $950.60