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	$92.59	9.374%	$101.2694	$101.27	$101.25	$101.30
Purchase #2	$73.68	9.820%	$80.9154	$80.92	$80.90	$80.90
Purchase #3	$91.76	9.510%	$100.4864	$100.49	$100.50	$100.50
Purchase #4	$177.48	6.146%	$188.3879	$188.39	$188.40	$188.40
Purchase #5	$169.60	3.860%	$176.1466	$176.15	$176.15	$176.10
Purchase #6	$149.88	10.515%	$165.6399	$165.64	$165.65	$165.60
Purchase #7	$230.68	11.170%	$256.447	$256.45	$256.45	$256.40
7 purchase totals =	$985.67		$1,069.2926	$1,069.31	$1,069.30	$1,069.20