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	$157.27	10.607%	$173.9516	$173.95	$173.95	$174.00
Purchase #2	$140.38	10.778%	$155.5102	$155.51	$155.50	$155.50
Purchase #3	$224.42	12.185%	$251.7656	$251.77	$251.75	$251.80
Purchase #4	$144.82	9.714%	$158.8878	$158.89	$158.90	$158.90
Purchase #5	$250.41	8.771%	$272.3735	$272.37	$272.35	$272.40
Purchase #6	$62.73	4.471%	$65.5347	$65.53	$65.55	$65.50
Purchase #7	$154.26	8.847%	$167.9074	$167.91	$167.90	$167.90
7 purchase totals =	$1,134.29		$1,245.9308	$1,245.93	$1,245.90	$1,246.00