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	$207.82	7.462%	$223.3275	$223.33	$223.35	$223.30
Purchase #2	$117.91	8.266%	$127.6564	$127.66	$127.65	$127.70
Purchase #3	$43.32	13.434%	$49.1396	$49.14	$49.15	$49.10
Purchase #4	$142.31	8.721%	$154.7209	$154.72	$154.70	$154.70
Purchase #5	$107.72	3.702%	$111.7078	$111.71	$111.70	$111.70
Purchase #6	$211.49	9.453%	$231.4821	$231.48	$231.50	$231.50
Purchase #7	$180.28	7.678%	$194.1219	$194.12	$194.10	$194.10
7 purchase totals =	$1,010.85		$1,092.1562	$1,092.16	$1,092.15	$1,092.10