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	$197.29	13.196%	$223.3244	$223.32	$223.30	$223.30
Purchase #2	$24.72	3.330%	$25.5432	$25.54	$25.55	$25.50
Purchase #3	$245.74	3.314%	$253.8838	$253.88	$253.90	$253.90
Purchase #4	$200.76	12.374%	$225.602	$225.60	$225.60	$225.60
Purchase #5	$166.65	4.397%	$173.9776	$173.98	$174.00	$174.00
Purchase #6	$205.86	13.437%	$233.5214	$233.52	$233.50	$233.50
Purchase #7	$143.61	5.295%	$151.2141	$151.21	$151.20	$151.20
7 purchase totals =	$1,184.63		$1,287.0665	$1,287.05	$1,287.05	$1,287.00