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	$151.66	7.146%	$162.4976	$162.50	$162.50	$162.50
Purchase #2	$110.50	6.173%	$117.3212	$117.32	$117.30	$117.30
Purchase #3	$28.32	4.728%	$29.659	$29.66	$29.65	$29.70
Purchase #4	$160.32	4.543%	$167.6033	$167.60	$167.60	$167.60
Purchase #5	$161.98	6.715%	$172.857	$172.86	$172.85	$172.90
Purchase #6	$141.93	6.533%	$151.2023	$151.20	$151.20	$151.20
Purchase #7	$111.36	10.753%	$123.3345	$123.33	$123.35	$123.30
7 purchase totals =	$866.07		$924.4749	$924.47	$924.45	$924.50