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	$202.54	4.413%	$211.4781	$211.48	$211.50	$211.50
Purchase #2	$222.54	5.450%	$234.6684	$234.67	$234.65	$234.70
Purchase #3	$75.80	13.167%	$85.7806	$85.78	$85.80	$85.80
Purchase #4	$99.30	12.263%	$111.4772	$111.48	$111.50	$111.50
Purchase #5	$141.91	7.696%	$152.8314	$152.83	$152.85	$152.80
Purchase #6	$107.48	6.204%	$114.1481	$114.15	$114.15	$114.10
Purchase #7	$205.36	13.698%	$233.4902	$233.49	$233.50	$233.50
7 purchase totals =	$1,054.93		$1,143.8740	$1,143.88	$1,143.95	$1,143.90