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 $105.32   8.478%   $114.249   $114.25   $114.25   $114.20  
  Purchase #2 $157.87   6.775%   $168.5657   $168.57   $168.55   $168.60  
  Purchase #3 $157.72   9.631%   $172.91   $172.91   $172.90   $172.90  
  Purchase #4 $186.52   4.119%   $194.2028   $194.20   $194.20   $194.20  
  Purchase #5 $205.64   4.863%   $215.6403   $215.64   $215.65   $215.60  
  Purchase #6 $211.61   9.626%   $231.9796   $231.98   $232.00   $232.00  
  Purchase #7 $44.44   4.629%   $46.4971   $46.50   $46.50   $46.50  
  7 purchase totals = $1,069.12       $1,144.0445   $1,144.05   $1,144.05   $1,144.00