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 $59.27   5.644%   $62.6152   $62.62   $62.60   $62.60  
  Purchase #2 $196.82   4.509%   $205.6946   $205.69   $205.70   $205.70  
  Purchase #3 $218.28   7.784%   $235.2709   $235.27   $235.25   $235.30  
  Purchase #4 $225.35   9.641%   $247.076   $247.08   $247.10   $247.10  
  Purchase #5 $227.65   6.422%   $242.2697   $242.27   $242.25   $242.30  
  Purchase #6 $226.97   7.119%   $243.128   $243.13   $243.15   $243.10  
  Purchase #7 $241.59   8.517%   $262.1662   $262.17   $262.15   $262.20  
  7 purchase totals = $1,395.93       $1,498.2206   $1,498.23   $1,498.20   $1,498.30