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 $58.91   5.831%   $62.345   $62.35   $62.35   $62.30  
  Purchase #2 $105.51   10.391%   $116.4735   $116.47   $116.45   $116.50  
  Purchase #3 $180.74   9.737%   $198.3387   $198.34   $198.35   $198.30  
  Purchase #4 $176.88   9.594%   $193.8499   $193.85   $193.85   $193.80  
  Purchase #5 $229.45   13.381%   $260.1527   $260.15   $260.15   $260.20  
  Purchase #6 $127.72   5.281%   $134.4649   $134.46   $134.45   $134.50  
  Purchase #7 $84.92   10.637%   $93.9529   $93.95   $93.95   $94.00  
  7 purchase totals = $964.13       $1,059.5776   $1,059.57   $1,059.55   $1,059.60