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	$181.83	10.140%	$200.2676	$200.27	$200.25	$200.30
Purchase #2	$174.41	5.741%	$184.4229	$184.42	$184.40	$184.40
Purchase #3	$111.85	3.674%	$115.9594	$115.96	$115.95	$116.00
Purchase #4	$50.37	11.294%	$56.0588	$56.06	$56.05	$56.10
Purchase #5	$167.54	3.548%	$173.4843	$173.48	$173.50	$173.50
Purchase #6	$147.76	3.833%	$153.4236	$153.42	$153.40	$153.40
Purchase #7	$140.70	8.615%	$152.8213	$152.82	$152.80	$152.80
7 purchase totals =	$974.46		$1,036.4379	$1,036.43	$1,036.35	$1,036.50