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	$145.95	4.818%	$152.9819	$152.98	$153.00	$153.00
Purchase #2	$225.26	13.346%	$255.3232	$255.32	$255.30	$255.30
Purchase #3	$28.88	11.276%	$32.1365	$32.14	$32.15	$32.10
Purchase #4	$226.88	9.144%	$247.6259	$247.63	$247.65	$247.60
Purchase #5	$49.33	3.217%	$50.9169	$50.92	$50.90	$50.90
Purchase #6	$223.98	8.126%	$242.1806	$242.18	$242.20	$242.20
Purchase #7	$100.32	3.753%	$104.085	$104.09	$104.10	$104.10
7 purchase totals =	$1,000.60		$1,085.2500	$1,085.26	$1,085.30	$1,085.20