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 $119.38   6.109%   $126.6729   $126.67   $126.65   $126.70  
  Purchase #2 $60.69   3.142%   $62.5969   $62.60   $62.60   $62.60  
  Purchase #3 $113.31   9.484%   $124.0563   $124.06   $124.05   $124.10  
  Purchase #4 $133.79   3.235%   $138.1181   $138.12   $138.10   $138.10  
  Purchase #5 $187.87   9.652%   $206.0032   $206.00   $206.00   $206.00  
  Purchase #6 $190.74   11.401%   $212.4863   $212.49   $212.50   $212.50  
  Purchase #7 $248.79   4.583%   $260.192   $260.19   $260.20   $260.20  
  7 purchase totals = $1,054.57       $1,130.1257   $1,130.13   $1,130.10   $1,130.20