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 $104.46   9.377%   $114.2552   $114.26   $114.25   $114.30  
  Purchase #2 $178.53   4.559%   $186.6692   $186.67   $186.65   $186.70  
  Purchase #3 $191.84   11.524%   $213.9476   $213.95   $213.95   $213.90  
  Purchase #4 $33.37   3.605%   $34.573   $34.57   $34.55   $34.60  
  Purchase #5 $198.27   11.826%   $221.7174   $221.72   $221.70   $221.70  
  Purchase #6 $153.50   5.121%   $161.3607   $161.36   $161.35   $161.40  
  Purchase #7 $187.96   3.224%   $194.0198   $194.02   $194.00   $194.00  
  7 purchase totals = $1,047.93       $1,126.5429   $1,126.55   $1,126.45   $1,126.60