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	$119.31	5.838%	$126.2753	$126.28	$126.30	$126.30
Purchase #2	$244.38	4.671%	$255.795	$255.80	$255.80	$255.80
Purchase #3	$241.62	4.251%	$251.8913	$251.89	$251.90	$251.90
Purchase #4	$32.32	9.850%	$35.5035	$35.50	$35.50	$35.50
Purchase #5	$53.34	10.833%	$59.1183	$59.12	$59.10	$59.10
Purchase #6	$185.43	3.196%	$191.3563	$191.36	$191.35	$191.40
Purchase #7	$211.68	12.448%	$238.0299	$238.03	$238.05	$238.00
7 purchase totals =	$1,088.08		$1,157.9696	$1,157.98	$1,158.00	$1,158.00