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	$125.58	5.788%	$132.8486	$132.85	$132.85	$132.80
Purchase #2	$193.35	10.677%	$213.994	$213.99	$214.00	$214.00
Purchase #3	$223.95	10.814%	$248.168	$248.17	$248.15	$248.20
Purchase #4	$247.54	7.362%	$265.7639	$265.76	$265.75	$265.80
Purchase #5	$46.84	9.160%	$51.1305	$51.13	$51.15	$51.10
Purchase #6	$39.33	7.102%	$42.1232	$42.12	$42.10	$42.10
Purchase #7	$52.35	13.738%	$59.5418	$59.54	$59.55	$59.50
7 purchase totals =	$928.94		$1,013.5700	$1,013.56	$1,013.55	$1,013.50