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	$195.41	9.276%	$213.5362	$213.54	$213.55	$213.50
Purchase #2	$239.43	4.471%	$250.1349	$250.13	$250.15	$250.10
Purchase #3	$143.80	8.436%	$155.931	$155.93	$155.95	$155.90
Purchase #4	$175.35	9.143%	$191.3823	$191.38	$191.40	$191.40
Purchase #5	$200.82	11.183%	$223.2777	$223.28	$223.30	$223.30
Purchase #6	$74.68	5.539%	$78.8165	$78.82	$78.80	$78.80
Purchase #7	$110.43	7.382%	$118.5819	$118.58	$118.60	$118.60
7 purchase totals =	$1,139.92		$1,231.6605	$1,231.66	$1,231.75	$1,231.60