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	$211.25	5.694%	$223.2786	$223.28	$223.30	$223.30
Purchase #2	$166.86	4.221%	$173.9032	$173.90	$173.90	$173.90
Purchase #3	$71.35	4.476%	$74.5436	$74.54	$74.55	$74.50
Purchase #4	$77.81	10.720%	$86.1512	$86.15	$86.15	$86.20
Purchase #5	$214.58	13.197%	$242.8981	$242.90	$242.90	$242.90
Purchase #6	$231.74	5.400%	$244.254	$244.25	$244.25	$244.30
Purchase #7	$123.86	6.248%	$131.5988	$131.60	$131.60	$131.60
7 purchase totals =	$1,097.45		$1,176.6275	$1,176.62	$1,176.65	$1,176.70