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	$184.57	5.563%	$194.8376	$194.84	$194.85	$194.80
Purchase #2	$74.49	5.386%	$78.502	$78.50	$78.50	$78.50
Purchase #3	$90.55	8.106%	$97.89	$97.89	$97.90	$97.90
Purchase #4	$123.27	3.632%	$127.7472	$127.75	$127.75	$127.70
Purchase #5	$159.52	10.343%	$176.0192	$176.02	$176.00	$176.00
Purchase #6	$48.69	3.358%	$50.325	$50.33	$50.35	$50.30
Purchase #7	$56.31	9.793%	$61.8244	$61.82	$61.80	$61.80
7 purchase totals =	$737.40		$787.1454	$787.15	$787.15	$787.00