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	$125.77	9.220%	$137.366	$137.37	$137.35	$137.40
Purchase #2	$148.27	12.197%	$166.3545	$166.35	$166.35	$166.40
Purchase #3	$88.69	13.620%	$100.7696	$100.77	$100.75	$100.80
Purchase #4	$84.86	4.514%	$88.6906	$88.69	$88.70	$88.70
Purchase #5	$211.77	5.123%	$222.619	$222.62	$222.60	$222.60
Purchase #6	$247.65	11.202%	$275.3918	$275.39	$275.40	$275.40
Purchase #7	$166.26	4.104%	$173.0833	$173.08	$173.10	$173.10
7 purchase totals =	$1,073.27		$1,164.2748	$1,164.27	$1,164.25	$1,164.40