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 $176.60   7.675%   $190.1541   $190.15   $190.15   $190.20  
  Purchase #2 $225.54   4.356%   $235.3645   $235.36   $235.35   $235.40  
  Purchase #3 $168.62   5.493%   $177.8823   $177.88   $177.90   $177.90  
  Purchase #4 $24.56   8.187%   $26.5707   $26.57   $26.55   $26.60  
  Purchase #5 $61.56   6.449%   $65.53   $65.53   $65.55   $65.50  
  Purchase #6 $144.80   8.253%   $156.7503   $156.75   $156.75   $156.80  
  Purchase #7 $224.91   7.597%   $241.9964   $242.00   $242.00   $242.00  
  7 purchase totals = $1,026.59       $1,094.2483   $1,094.24   $1,094.25   $1,094.40