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 $58.81   7.151%   $63.0155   $63.02   $63.00   $63.00  
  Purchase #2 $214.56   9.450%   $234.8359   $234.84   $234.85   $234.80  
  Purchase #3 $173.71   12.297%   $195.0711   $195.07   $195.05   $195.10  
  Purchase #4 $222.46   8.572%   $241.5293   $241.53   $241.55   $241.50  
  Purchase #5 $136.41   9.173%   $148.9229   $148.92   $148.90   $148.90  
  Purchase #6 $50.94   4.286%   $53.1233   $53.12   $53.10   $53.10  
  Purchase #7 $176.25   12.385%   $198.0786   $198.08   $198.10   $198.10  
  7 purchase totals = $1,033.14       $1,134.5766   $1,134.58   $1,134.55   $1,134.50