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	$198.49	5.115%	$208.6428	$208.64	$208.65	$208.60
Purchase #2	$128.55	4.735%	$134.6368	$134.64	$134.65	$134.60
Purchase #3	$70.36	11.419%	$78.3944	$78.39	$78.40	$78.40
Purchase #4	$9.98	5.282%	$10.5071	$10.51	$10.50	$10.50
Purchase #5	$241.44	7.455%	$259.4394	$259.44	$259.45	$259.40
Purchase #6	$156.64	6.114%	$166.217	$166.22	$166.20	$166.20
Purchase #7	$130.83	10.766%	$144.9152	$144.92	$144.90	$144.90
7 purchase totals =	$936.29		$1,002.7527	$1,002.76	$1,002.75	$1,002.60