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 $216.79   5.557%   $228.837   $228.84   $228.85   $228.80  
  Purchase #2 $217.77   4.271%   $227.071   $227.07   $227.05   $227.10  
  Purchase #3 $98.43   4.609%   $102.9666   $102.97   $102.95   $103.00  
  Purchase #4 $230.68   5.497%   $243.3605   $243.36   $243.35   $243.40  
  Purchase #5 $94.87   4.116%   $98.7748   $98.77   $98.75   $98.80  
  Purchase #6 $167.96   3.354%   $173.5934   $173.59   $173.60   $173.60  
  Purchase #7 $134.97   13.688%   $153.4447   $153.44   $153.45   $153.40  
  7 purchase totals = $1,161.47       $1,228.0480   $1,228.04   $1,228.00   $1,228.10