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	$153.47	13.360%	$173.9736	$173.97	$173.95	$174.00
Purchase #2	$102.87	11.237%	$114.4295	$114.43	$114.45	$114.40
Purchase #3	$11.91	8.595%	$12.9337	$12.93	$12.95	$12.90
Purchase #4	$13.96	9.444%	$15.2784	$15.28	$15.30	$15.30
Purchase #5	$44.74	10.212%	$49.3088	$49.31	$49.30	$49.30
Purchase #6	$33.96	9.621%	$37.2273	$37.23	$37.25	$37.20
Purchase #7	$82.33	9.263%	$89.9562	$89.96	$89.95	$90.00
7 purchase totals =	$443.24		$493.1075	$493.11	$493.15	$493.10