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	$208.38	3.855%	$216.413	$216.41	$216.40	$216.40
Purchase #2	$89.75	11.871%	$100.4042	$100.40	$100.40	$100.40
Purchase #3	$139.31	12.358%	$156.5259	$156.53	$156.55	$156.50
Purchase #4	$184.65	12.408%	$207.5614	$207.56	$207.55	$207.60
Purchase #5	$228.59	11.108%	$253.9818	$253.98	$254.00	$254.00
Purchase #6	$151.62	4.539%	$158.502	$158.50	$158.50	$158.50
Purchase #7	$191.59	10.311%	$211.3448	$211.34	$211.35	$211.30
7 purchase totals =	$1,193.89		$1,304.7331	$1,304.72	$1,304.75	$1,304.70