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	$172.52	7.410%	$185.3037	$185.30	$185.30	$185.30
Purchase #2	$125.62	3.487%	$130.0004	$130.00	$130.00	$130.00
Purchase #3	$241.55	5.385%	$254.5575	$254.56	$254.55	$254.60
Purchase #4	$13.50	5.579%	$14.2532	$14.25	$14.25	$14.30
Purchase #5	$62.99	13.489%	$71.4867	$71.49	$71.50	$71.50
Purchase #6	$205.70	13.493%	$233.4551	$233.46	$233.45	$233.50
Purchase #7	$239.46	6.850%	$255.863	$255.86	$255.85	$255.90
7 purchase totals =	$1,061.34		$1,144.9196	$1,144.92	$1,144.90	$1,145.10