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	$68.88	10.824%	$76.3356	$76.34	$76.35	$76.30
Purchase #2	$176.64	10.468%	$195.1307	$195.13	$195.15	$195.10
Purchase #3	$211.32	8.624%	$229.5442	$229.54	$229.55	$229.50
Purchase #4	$109.52	8.371%	$118.6879	$118.69	$118.70	$118.70
Purchase #5	$241.32	12.828%	$272.2765	$272.28	$272.30	$272.30
Purchase #6	$53.37	11.833%	$59.6853	$59.69	$59.70	$59.70
Purchase #7	$116.40	6.156%	$123.5656	$123.57	$123.55	$123.60
7 purchase totals =	$977.45		$1,075.2258	$1,075.24	$1,075.30	$1,075.20