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	$168.56	4.847%	$176.7301	$176.73	$176.75	$176.70
Purchase #2	$102.87	8.141%	$111.2446	$111.24	$111.25	$111.20
Purchase #3	$159.60	11.106%	$177.3252	$177.33	$177.35	$177.30
Purchase #4	$99.54	10.683%	$110.1739	$110.17	$110.15	$110.20
Purchase #5	$201.91	10.485%	$223.0803	$223.08	$223.10	$223.10
Purchase #6	$59.52	8.293%	$64.456	$64.46	$64.45	$64.50
Purchase #7	$99.54	6.157%	$105.6687	$105.67	$105.65	$105.70
7 purchase totals =	$891.54		$968.6788	$968.68	$968.70	$968.70