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	$244.39	4.118%	$254.454	$254.45	$254.45	$254.50
Purchase #2	$233.35	6.228%	$247.883	$247.88	$247.90	$247.90
Purchase #3	$97.40	8.478%	$105.6576	$105.66	$105.65	$105.70
Purchase #4	$141.54	8.191%	$153.1335	$153.13	$153.15	$153.10
Purchase #5	$175.48	11.860%	$196.2919	$196.29	$196.30	$196.30
Purchase #6	$193.90	5.468%	$204.5025	$204.50	$204.50	$204.50
Purchase #7	$229.72	13.646%	$261.0676	$261.07	$261.05	$261.10
7 purchase totals =	$1,315.78		$1,422.9901	$1,422.98	$1,423.00	$1,423.10