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	$208.70	11.805%	$233.337	$233.34	$233.35	$233.30
Purchase #2	$99.75	7.341%	$107.0726	$107.07	$107.05	$107.10
Purchase #3	$82.32	5.467%	$86.8204	$86.82	$86.80	$86.80
Purchase #4	$235.68	7.153%	$252.5382	$252.54	$252.55	$252.50
Purchase #5	$85.52	4.182%	$89.0964	$89.10	$89.10	$89.10
Purchase #6	$112.72	11.364%	$125.5295	$125.53	$125.55	$125.50
Purchase #7	$112.72	13.490%	$127.9259	$127.93	$127.95	$127.90
7 purchase totals =	$937.41		$1,022.3200	$1,022.33	$1,022.35	$1,022.20