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 $213.98   10.229%   $235.868   $235.87   $235.85   $235.90  
  Purchase #2 $119.99   8.449%   $130.128   $130.13   $130.15   $130.10  
  Purchase #3 $32.98   4.661%   $34.5172   $34.52   $34.50   $34.50  
  Purchase #4 $99.28   7.226%   $106.454   $106.45   $106.45   $106.50  
  Purchase #5 $171.52   7.654%   $184.6481   $184.65   $184.65   $184.60  
  Purchase #6 $181.55   13.844%   $206.6838   $206.68   $206.70   $206.70  
  Purchase #7 $249.74   7.178%   $267.6663   $267.67   $267.65   $267.70  
  7 purchase totals = $1,069.04       $1,165.9654   $1,165.97   $1,165.95   $1,166.00