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 $62.50   9.495%   $68.4344   $68.43   $68.45   $68.40  
  Purchase #2 $203.62   6.439%   $216.7311   $216.73   $216.75   $216.70  
  Purchase #3 $103.62   9.669%   $113.639   $113.64   $113.65   $113.60  
  Purchase #4 $192.99   9.465%   $211.2565   $211.26   $211.25   $211.30  
  Purchase #5 $246.26   12.129%   $276.1289   $276.13   $276.15   $276.10  
  Purchase #6 $88.36   10.338%   $97.4947   $97.49   $97.50   $97.50  
  Purchase #7 $166.34   4.197%   $173.3213   $173.32   $173.30   $173.30  
  7 purchase totals = $1,063.69       $1,157.0059   $1,157.00   $1,157.05   $1,156.90