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	$227.62	7.281%	$244.193	$244.19	$244.20	$244.20
Purchase #2	$82.82	8.119%	$89.5442	$89.54	$89.55	$89.50
Purchase #3	$235.52	11.653%	$262.9651	$262.97	$262.95	$263.00
Purchase #4	$189.38	3.586%	$196.1712	$196.17	$196.15	$196.20
Purchase #5	$43.43	11.597%	$48.4666	$48.47	$48.45	$48.50
Purchase #6	$195.74	12.486%	$220.1801	$220.18	$220.20	$220.20
Purchase #7	$105.75	4.592%	$110.606	$110.61	$110.60	$110.60
7 purchase totals =	$1,080.26		$1,172.1262	$1,172.13	$1,172.10	$1,172.20