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 $161.59   7.680%   $174.0001   $174.00   $174.00   $174.00  
  Purchase #2 $197.69   4.112%   $205.819   $205.82   $205.80   $205.80  
  Purchase #3 $17.76   3.266%   $18.34   $18.34   $18.35   $18.30  
  Purchase #4 $211.57   5.232%   $222.6393   $222.64   $222.65   $222.60  
  Purchase #5 $64.33   5.670%   $67.9775   $67.98   $68.00   $68.00  
  Purchase #6 $213.37   8.420%   $231.3358   $231.34   $231.35   $231.30  
  Purchase #7 $201.40   4.724%   $210.9141   $210.91   $210.90   $210.90  
  7 purchase totals = $1,067.71       $1,131.0258   $1,131.03   $1,131.05   $1,130.90