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	$217.54	9.756%	$238.7632	$238.76	$238.75	$238.80
Purchase #2	$220.79	9.435%	$241.6215	$241.62	$241.60	$241.60
Purchase #3	$156.76	6.373%	$166.7503	$166.75	$166.75	$166.80
Purchase #4	$224.90	8.132%	$243.1889	$243.19	$243.20	$243.20
Purchase #5	$181.68	5.350%	$191.3999	$191.40	$191.40	$191.40
Purchase #6	$214.82	6.803%	$229.4342	$229.43	$229.45	$229.40
Purchase #7	$127.87	3.124%	$131.8647	$131.86	$131.85	$131.90
7 purchase totals =	$1,344.36		$1,443.0227	$1,443.01	$1,443.00	$1,443.10