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	$178.71	9.447%	$195.5927	$195.59	$195.60	$195.60
Purchase #2	$211.83	5.411%	$223.2921	$223.29	$223.30	$223.30
Purchase #3	$228.75	6.736%	$244.1586	$244.16	$244.15	$244.20
Purchase #4	$203.68	9.305%	$222.6324	$222.63	$222.65	$222.60
Purchase #5	$144.81	4.383%	$151.157	$151.16	$151.15	$151.20
Purchase #6	$151.82	3.316%	$156.8544	$156.85	$156.85	$156.90
Purchase #7	$68.73	4.230%	$71.6373	$71.64	$71.65	$71.60
7 purchase totals =	$1,188.33		$1,265.3245	$1,265.32	$1,265.35	$1,265.40