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	$126.95	3.479%	$131.3666	$131.37	$131.35	$131.40
Purchase #2	$146.75	10.788%	$162.5814	$162.58	$162.60	$162.60
Purchase #3	$23.29	7.843%	$25.1166	$25.12	$25.10	$25.10
Purchase #4	$11.62	6.244%	$12.3456	$12.35	$12.35	$12.30
Purchase #5	$106.46	4.525%	$111.2773	$111.28	$111.30	$111.30
Purchase #6	$215.35	5.172%	$226.4879	$226.49	$226.50	$226.50
Purchase #7	$72.54	13.139%	$82.071	$82.07	$82.05	$82.10
7 purchase totals =	$702.96		$751.2464	$751.26	$751.25	$751.30