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 $32.94   9.113%   $35.9418   $35.94   $35.95   $35.90  
  Purchase #2 $211.79   7.247%   $227.1384   $227.14   $227.15   $227.10  
  Purchase #3 $126.40   5.357%   $133.1712   $133.17   $133.15   $133.20  
  Purchase #4 $242.47   12.177%   $271.9956   $272.00   $272.00   $272.00  
  Purchase #5 $82.62   6.325%   $87.8457   $87.85   $87.85   $87.80  
  Purchase #6 $214.73   10.365%   $236.9868   $236.99   $237.00   $237.00  
  Purchase #7 $166.44   5.453%   $175.516   $175.52   $175.50   $175.50  
  7 purchase totals = $1,077.39       $1,168.5955   $1,168.61   $1,168.60   $1,168.50