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	$143.59	7.222%	$153.9601	$153.96	$153.95	$154.00
Purchase #2	$120.92	9.525%	$132.4376	$132.44	$132.45	$132.40
Purchase #3	$176.58	11.639%	$197.1321	$197.13	$197.15	$197.10
Purchase #4	$234.58	9.113%	$255.9573	$255.96	$255.95	$256.00
Purchase #5	$27.89	5.131%	$29.321	$29.32	$29.30	$29.30
Purchase #6	$95.49	5.385%	$100.6321	$100.63	$100.65	$100.60
Purchase #7	$211.29	5.439%	$222.7821	$222.78	$222.80	$222.80
7 purchase totals =	$1,010.34		$1,092.2223	$1,092.22	$1,092.25	$1,092.20