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	$167.71	4.365%	$175.0305	$175.03	$175.05	$175.00
Purchase #2	$127.54	7.701%	$137.3619	$137.36	$137.35	$137.40
Purchase #3	$123.76	4.476%	$129.2995	$129.30	$129.30	$129.30
Purchase #4	$147.45	5.692%	$155.8429	$155.84	$155.85	$155.80
Purchase #5	$98.85	12.852%	$111.5542	$111.55	$111.55	$111.60
Purchase #6	$58.49	5.573%	$61.7496	$61.75	$61.75	$61.70
Purchase #7	$111.54	11.719%	$124.6114	$124.61	$124.60	$124.60
7 purchase totals =	$835.34		$895.4500	$895.44	$895.45	$895.40