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 $88.68   8.348%   $96.083   $96.08   $96.10   $96.10  
  Purchase #2 $162.31   11.259%   $180.5845   $180.58   $180.60   $180.60  
  Purchase #3 $186.94   6.222%   $198.5714   $198.57   $198.55   $198.60  
  Purchase #4 $212.89   10.776%   $235.831   $235.83   $235.85   $235.80  
  Purchase #5 $207.78   13.241%   $235.2921   $235.29   $235.30   $235.30  
  Purchase #6 $106.92   5.162%   $112.4392   $112.44   $112.45   $112.40  
  Purchase #7 $104.43   10.175%   $115.0558   $115.06   $115.05   $115.10  
  7 purchase totals = $1,069.95       $1,173.8570   $1,173.85   $1,173.90   $1,173.90