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	$210.47	5.741%	$222.5531	$222.55	$222.55	$222.60
Purchase #2	$47.87	13.401%	$54.2851	$54.29	$54.30	$54.30
Purchase #3	$32.53	6.428%	$34.621	$34.62	$34.60	$34.60
Purchase #4	$161.35	8.340%	$174.8066	$174.81	$174.80	$174.80
Purchase #5	$234.76	6.707%	$250.5054	$250.51	$250.50	$250.50
Purchase #6	$174.85	10.285%	$192.8333	$192.83	$192.85	$192.80
Purchase #7	$166.46	7.202%	$178.4484	$178.45	$178.45	$178.40
7 purchase totals =	$1,028.29		$1,108.0529	$1,108.06	$1,108.05	$1,108.00