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 $96.69   5.232%   $101.7488   $101.75   $101.75   $101.70  
  Purchase #2 $231.78   5.463%   $244.4421   $244.44   $244.45   $244.40  
  Purchase #3 $225.29   6.125%   $239.089   $239.09   $239.10   $239.10  
  Purchase #4 $12.50   13.819%   $14.2274   $14.23   $14.25   $14.20  
  Purchase #5 $208.48   5.111%   $219.1354   $219.14   $219.15   $219.10  
  Purchase #6 $174.31   5.328%   $183.5972   $183.60   $183.60   $183.60  
  Purchase #7 $147.53   9.111%   $160.9715   $160.97   $160.95   $161.00  
  7 purchase totals = $1,096.58       $1,163.2114   $1,163.22   $1,163.25   $1,163.10