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 $58.85   5.489%   $62.0803   $62.08   $62.10   $62.10  
  Purchase #2 $63.40   11.847%   $70.911   $70.91   $70.90   $70.90  
  Purchase #3 $174.71   13.531%   $198.35   $198.35   $198.35   $198.40  
  Purchase #4 $160.67   9.366%   $175.7184   $175.72   $175.70   $175.70  
  Purchase #5 $200.79   6.734%   $214.3112   $214.31   $214.30   $214.30  
  Purchase #6 $96.65   6.836%   $103.257   $103.26   $103.25   $103.30  
  Purchase #7 $227.51   4.726%   $238.2621   $238.26   $238.25   $238.30  
  7 purchase totals = $982.58       $1,062.8900   $1,062.89   $1,062.85   $1,063.00