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	$79.31	4.613%	$82.9686	$82.97	$82.95	$83.00
Purchase #2	$60.66	11.670%	$67.739	$67.74	$67.75	$67.70
Purchase #3	$214.77	4.137%	$223.655	$223.66	$223.65	$223.70
Purchase #4	$120.32	5.869%	$127.3816	$127.38	$127.40	$127.40
Purchase #5	$157.25	5.249%	$165.5041	$165.50	$165.50	$165.50
Purchase #6	$233.89	4.131%	$243.552	$243.55	$243.55	$243.60
Purchase #7	$45.92	11.325%	$51.1204	$51.12	$51.10	$51.10
7 purchase totals =	$912.12		$961.9207	$961.92	$961.90	$962.00