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	$178.97	10.361%	$197.5131	$197.51	$197.50	$197.50
Purchase #2	$232.85	6.284%	$247.4823	$247.48	$247.50	$247.50
Purchase #3	$144.89	10.781%	$160.5106	$160.51	$160.50	$160.50
Purchase #4	$164.42	5.584%	$173.6012	$173.60	$173.60	$173.60
Purchase #5	$134.36	6.847%	$143.5596	$143.56	$143.55	$143.60
Purchase #6	$158.28	13.804%	$180.129	$180.13	$180.15	$180.10
Purchase #7	$55.44	7.604%	$59.6557	$59.66	$59.65	$59.70
7 purchase totals =	$1,069.21		$1,162.4515	$1,162.45	$1,162.45	$1,162.50