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	$197.89	10.480%	$218.6289	$218.63	$218.65	$218.60
Purchase #2	$50.44	5.699%	$53.3146	$53.31	$53.30	$53.30
Purchase #3	$103.26	7.791%	$111.305	$111.31	$111.30	$111.30
Purchase #4	$151.28	4.494%	$158.0785	$158.08	$158.10	$158.10
Purchase #5	$174.54	3.315%	$180.326	$180.33	$180.35	$180.30
Purchase #6	$216.94	5.178%	$228.1732	$228.17	$228.15	$228.20
Purchase #7	$96.69	12.230%	$108.5152	$108.52	$108.50	$108.50
7 purchase totals =	$991.04		$1,058.3414	$1,058.35	$1,058.35	$1,058.30