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	$185.36	4.850%	$194.35	$194.35	$194.35	$194.40
Purchase #2	$204.31	10.425%	$225.6093	$225.61	$225.60	$225.60
Purchase #3	$13.89	6.672%	$14.8167	$14.82	$14.80	$14.80
Purchase #4	$145.81	4.461%	$152.3146	$152.31	$152.30	$152.30
Purchase #5	$84.89	8.498%	$92.104	$92.10	$92.10	$92.10
Purchase #6	$227.90	11.640%	$254.4276	$254.43	$254.45	$254.40
Purchase #7	$77.97	3.379%	$80.6046	$80.60	$80.60	$80.60
7 purchase totals =	$940.13		$1,014.2268	$1,014.22	$1,014.20	$1,014.20