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	$196.56	13.656%	$223.4022	$223.40	$223.40	$223.40
Purchase #2	$174.27	6.406%	$185.4337	$185.43	$185.45	$185.40
Purchase #3	$23.42	8.321%	$25.3688	$25.37	$25.35	$25.40
Purchase #4	$138.57	13.518%	$157.3019	$157.30	$157.30	$157.30
Purchase #5	$241.75	8.856%	$263.1594	$263.16	$263.15	$263.20
Purchase #6	$132.83	3.231%	$137.1217	$137.12	$137.10	$137.10
Purchase #7	$39.51	5.328%	$41.6151	$41.62	$41.60	$41.60
7 purchase totals =	$946.91		$1,033.4028	$1,033.40	$1,033.35	$1,033.40