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 $87.69   8.421%   $95.0744   $95.07   $95.05   $95.10  
  Purchase #2 $5.28   5.807%   $5.5866   $5.59   $5.60   $5.60  
  Purchase #3 $214.86   3.343%   $222.0428   $222.04   $222.05   $222.00  
  Purchase #4 $218.31   5.693%   $230.7384   $230.74   $230.75   $230.70  
  Purchase #5 $243.84   7.653%   $262.5011   $262.50   $262.50   $262.50  
  Purchase #6 $175.77   8.227%   $190.2306   $190.23   $190.25   $190.20  
  Purchase #7 $128.94   13.745%   $146.6628   $146.66   $146.65   $146.70  
  7 purchase totals = $1,074.69       $1,152.8367   $1,152.83   $1,152.85   $1,152.80