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	$134.95	12.647%	$152.0171	$152.02	$152.00	$152.00
Purchase #2	$234.98	7.831%	$253.3813	$253.38	$253.40	$253.40
Purchase #3	$235.52	4.257%	$245.5461	$245.55	$245.55	$245.50
Purchase #4	$85.47	4.468%	$89.2888	$89.29	$89.30	$89.30
Purchase #5	$184.84	4.121%	$192.4573	$192.46	$192.45	$192.50
Purchase #6	$144.28	5.189%	$151.7667	$151.77	$151.75	$151.80
Purchase #7	$18.36	12.214%	$20.6025	$20.60	$20.60	$20.60
7 purchase totals =	$1,038.40		$1,105.0598	$1,105.07	$1,105.05	$1,105.10