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 $60.36   3.127%   $62.2475   $62.25   $62.25   $62.20  
  Purchase #2 $247.46   8.751%   $269.1152   $269.12   $269.10   $269.10  
  Purchase #3 $49.28   7.834%   $53.1406   $53.14   $53.15   $53.10  
  Purchase #4 $192.85   3.801%   $200.1802   $200.18   $200.20   $200.20  
  Purchase #5 $120.98   8.528%   $131.2972   $131.30   $131.30   $131.30  
  Purchase #6 $111.27   13.848%   $126.6787   $126.68   $126.70   $126.70  
  Purchase #7 $24.84   8.171%   $26.8697   $26.87   $26.85   $26.90  
  7 purchase totals = $807.04       $869.5291   $869.54   $869.55   $869.50