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 $195.85   4.659%   $204.9747   $204.97   $204.95   $205.00  
  Purchase #2 $96.89   4.325%   $101.0805   $101.08   $101.10   $101.10  
  Purchase #3 $205.64   7.749%   $221.575   $221.58   $221.60   $221.60  
  Purchase #4 $166.65   9.337%   $182.2101   $182.21   $182.20   $182.20  
  Purchase #5 $196.61   6.260%   $208.9178   $208.92   $208.90   $208.90  
  Purchase #6 $150.62   12.485%   $169.4249   $169.42   $169.40   $169.40  
  Purchase #7 $146.33   7.670%   $157.5535   $157.55   $157.55   $157.60  
  7 purchase totals = $1,158.59       $1,245.7365   $1,245.73   $1,245.70   $1,245.80