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	$48.56	8.339%	$52.6094	$52.61	$52.60	$52.60
Purchase #2	$27.65	4.546%	$28.907	$28.91	$28.90	$28.90
Purchase #3	$100.68	11.385%	$112.1424	$112.14	$112.15	$112.10
Purchase #4	$219.75	4.192%	$228.9619	$228.96	$228.95	$229.00
Purchase #5	$57.44	8.416%	$62.2742	$62.27	$62.25	$62.30
Purchase #6	$50.58	4.778%	$52.9967	$53.00	$53.00	$53.00
Purchase #7	$180.50	8.823%	$196.4255	$196.43	$196.45	$196.40
7 purchase totals =	$685.16		$734.3171	$734.32	$734.30	$734.30