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 $179.38   8.712%   $195.0076   $195.01   $195.00   $195.00  
  Purchase #2 $166.66   7.846%   $179.7361   $179.74   $179.75   $179.70  
  Purchase #3 $234.83   4.135%   $244.5402   $244.54   $244.55   $244.50  
  Purchase #4 $96.80   5.634%   $102.2537   $102.25   $102.25   $102.30  
  Purchase #5 $49.32   5.687%   $52.1248   $52.12   $52.10   $52.10  
  Purchase #6 $60.45   5.350%   $63.6841   $63.68   $63.70   $63.70  
  Purchase #7 $250.61   3.213%   $258.6621   $258.66   $258.65   $258.70  
  7 purchase totals = $1,038.05       $1,096.0086   $1,096.00   $1,096.00   $1,096.00