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 $206.76   7.468%   $222.2008   $222.20   $222.20   $222.20  
  Purchase #2 $243.94   13.594%   $277.1012   $277.10   $277.10   $277.10  
  Purchase #3 $6.95   6.124%   $7.3756   $7.38   $7.40   $7.40  
  Purchase #4 $212.75   7.236%   $228.1446   $228.14   $228.15   $228.10  
  Purchase #5 $192.71   5.142%   $202.6191   $202.62   $202.60   $202.60  
  Purchase #6 $162.28   7.552%   $174.5354   $174.54   $174.55   $174.50  
  Purchase #7 $88.65   8.408%   $96.1037   $96.10   $96.10   $96.10  
  7 purchase totals = $1,114.04       $1,208.0804   $1,208.08   $1,208.10   $1,208.00