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 $85.86   10.771%   $95.108   $95.11   $95.10   $95.10  
  Purchase #2 $208.89   5.854%   $221.1184   $221.12   $221.10   $221.10  
  Purchase #3 $63.51   4.434%   $66.326   $66.33   $66.35   $66.30  
  Purchase #4 $114.68   3.388%   $118.5654   $118.57   $118.55   $118.60  
  Purchase #5 $245.70   6.199%   $260.9309   $260.93   $260.95   $260.90  
  Purchase #6 $195.31   9.695%   $214.2453   $214.25   $214.25   $214.20  
  Purchase #7 $122.49   12.260%   $137.5073   $137.51   $137.50   $137.50  
  7 purchase totals = $1,036.44       $1,113.8013   $1,113.82   $1,113.80   $1,113.70