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	$58.37	5.625%	$61.6533	$61.65	$61.65	$61.70
Purchase #2	$209.79	13.695%	$238.5207	$238.52	$238.50	$238.50
Purchase #3	$159.59	10.447%	$176.2624	$176.26	$176.25	$176.30
Purchase #4	$228.99	11.287%	$254.8361	$254.84	$254.85	$254.80
Purchase #5	$205.46	8.479%	$222.881	$222.88	$222.90	$222.90
Purchase #6	$211.92	13.660%	$240.8683	$240.87	$240.85	$240.90
Purchase #7	$214.44	11.178%	$238.4101	$238.41	$238.40	$238.40
7 purchase totals =	$1,288.56		$1,433.4319	$1,433.43	$1,433.40	$1,433.50