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	$186.72	4.287%	$194.7247	$194.72	$194.70	$194.70
Purchase #2	$236.81	5.426%	$249.6593	$249.66	$249.65	$249.70
Purchase #3	$164.39	5.512%	$173.4512	$173.45	$173.45	$173.50
Purchase #4	$56.29	10.680%	$62.3018	$62.30	$62.30	$62.30
Purchase #5	$112.51	3.598%	$116.5581	$116.56	$116.55	$116.60
Purchase #6	$213.53	3.195%	$220.3523	$220.35	$220.35	$220.40
Purchase #7	$123.38	6.449%	$131.3368	$131.34	$131.35	$131.30
7 purchase totals =	$1,093.63		$1,148.3842	$1,148.38	$1,148.35	$1,148.50