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	$192.54	4.207%	$200.6402	$200.64	$200.65	$200.60
Purchase #2	$48.92	11.392%	$54.493	$54.49	$54.50	$54.50
Purchase #3	$228.27	6.600%	$243.3358	$243.34	$243.35	$243.30
Purchase #4	$73.83	8.513%	$80.1151	$80.12	$80.10	$80.10
Purchase #5	$102.65	4.336%	$107.1009	$107.10	$107.10	$107.10
Purchase #6	$238.58	6.316%	$253.6487	$253.65	$253.65	$253.60
Purchase #7	$134.39	6.192%	$142.7114	$142.71	$142.70	$142.70
7 purchase totals =	$1,019.18		$1,082.0451	$1,082.05	$1,082.05	$1,081.90