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 $88.38   8.344%   $95.7544   $95.75   $95.75   $95.80  
  Purchase #2 $192.47   4.743%   $201.5989   $201.60   $201.60   $201.60  
  Purchase #3 $79.47   3.719%   $82.4255   $82.43   $82.45   $82.40  
  Purchase #4 $36.29   4.274%   $37.841   $37.84   $37.85   $37.80  
  Purchase #5 $10.50   8.160%   $11.3568   $11.36   $11.35   $11.40  
  Purchase #6 $5.63   7.657%   $6.0611   $6.06   $6.05   $6.10  
  Purchase #7 $48.82   10.358%   $53.8768   $53.88   $53.90   $53.90  
  7 purchase totals = $461.56       $488.9145   $488.92   $488.95   $489.00