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	$95.59	11.244%	$106.3381	$106.34	$106.35	$106.30
Purchase #2	$162.97	6.463%	$173.5028	$173.50	$173.50	$173.50
Purchase #3	$119.87	5.499%	$126.4617	$126.46	$126.45	$126.50
Purchase #4	$202.67	9.737%	$222.404	$222.40	$222.40	$222.40
Purchase #5	$120.85	5.346%	$127.3106	$127.31	$127.30	$127.30
Purchase #6	$34.93	13.839%	$39.764	$39.76	$39.75	$39.80
Purchase #7	$17.84	9.596%	$19.5519	$19.55	$19.55	$19.60
7 purchase totals =	$754.72		$815.3331	$815.32	$815.30	$815.40