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	$205.33	4.387%	$214.3378	$214.34	$214.35	$214.30
Purchase #2	$168.76	4.495%	$176.3458	$176.35	$176.35	$176.30
Purchase #3	$144.64	11.251%	$160.9134	$160.91	$160.90	$160.90
Purchase #4	$142.56	11.729%	$159.2809	$159.28	$159.30	$159.30
Purchase #5	$106.80	4.658%	$111.7747	$111.77	$111.75	$111.80
Purchase #6	$229.32	11.868%	$256.5357	$256.54	$256.55	$256.50
Purchase #7	$127.52	11.252%	$141.8686	$141.87	$141.85	$141.90
7 purchase totals =	$1,124.93		$1,221.0569	$1,221.06	$1,221.05	$1,221.00