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 $44.63   3.841%   $46.3442   $46.34   $46.35   $46.30  
  Purchase #2 $90.53   9.133%   $98.7981   $98.80   $98.80   $98.80  
  Purchase #3 $53.39   7.798%   $57.5534   $57.55   $57.55   $57.60  
  Purchase #4 $48.59   8.413%   $52.6779   $52.68   $52.70   $52.70  
  Purchase #5 $209.54   10.780%   $232.1284   $232.13   $232.15   $232.10  
  Purchase #6 $188.55   10.847%   $209.002   $209.00   $209.00   $209.00  
  Purchase #7 $64.79   6.718%   $69.1426   $69.14   $69.15   $69.10  
  7 purchase totals = $700.02       $765.6466   $765.64   $765.70   $765.60