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 $216.44   4.856%   $226.9503   $226.95   $226.95   $227.00  
  Purchase #2 $53.77   6.149%   $57.0763   $57.08   $57.10   $57.10  
  Purchase #3 $85.56   12.724%   $96.4467   $96.45   $96.45   $96.40  
  Purchase #4 $137.28   9.747%   $150.6607   $150.66   $150.65   $150.70  
  Purchase #5 $104.57   7.426%   $112.3354   $112.34   $112.35   $112.30  
  Purchase #6 $203.52   6.129%   $215.9937   $215.99   $216.00   $216.00  
  Purchase #7 $178.41   4.539%   $186.508   $186.51   $186.50   $186.50  
  7 purchase totals = $979.55       $1,045.9711   $1,045.98   $1,046.00   $1,046.00