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	$214.41	9.777%	$235.3729	$235.37	$235.35	$235.40
Purchase #2	$166.95	4.200%	$173.9619	$173.96	$173.95	$174.00
Purchase #3	$45.55	4.700%	$47.6909	$47.69	$47.70	$47.70
Purchase #4	$105.68	8.715%	$114.89	$114.89	$114.90	$114.90
Purchase #5	$64.90	11.504%	$72.3661	$72.37	$72.35	$72.40
Purchase #6	$217.40	11.666%	$242.7619	$242.76	$242.75	$242.80
Purchase #7	$100.65	13.431%	$114.1683	$114.17	$114.15	$114.20
7 purchase totals =	$915.54		$1,001.2120	$1,001.21	$1,001.15	$1,001.40