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 $84.44   12.622%   $95.098   $95.10   $95.10   $95.10  
  Purchase #2 $92.38   4.281%   $96.3348   $96.33   $96.35   $96.30  
  Purchase #3 $151.48   6.566%   $161.4262   $161.43   $161.45   $161.40  
  Purchase #4 $57.26   11.788%   $64.0098   $64.01   $64.00   $64.00  
  Purchase #5 $144.51   10.670%   $159.9292   $159.93   $159.95   $159.90  
  Purchase #6 $238.25   3.169%   $245.8001   $245.80   $245.80   $245.80  
  Purchase #7 $224.46   7.376%   $241.0162   $241.02   $241.00   $241.00  
  7 purchase totals = $992.78       $1,063.6143   $1,063.62   $1,063.65   $1,063.50