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	$168.81	3.166%	$174.1545	$174.15	$174.15	$174.20
Purchase #2	$75.29	4.510%	$78.6856	$78.69	$78.70	$78.70
Purchase #3	$160.58	5.381%	$169.2208	$169.22	$169.20	$169.20
Purchase #4	$224.55	13.664%	$255.2325	$255.23	$255.25	$255.20
Purchase #5	$155.82	11.435%	$173.638	$173.64	$173.65	$173.60
Purchase #6	$116.99	12.225%	$131.292	$131.29	$131.30	$131.30
Purchase #7	$188.62	13.618%	$214.3063	$214.31	$214.30	$214.30
7 purchase totals =	$1,090.66		$1,196.5297	$1,196.53	$1,196.55	$1,196.50