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	$211.50	11.112%	$235.0019	$235.00	$235.00	$235.00
Purchase #2	$86.93	5.508%	$91.7181	$91.72	$91.70	$91.70
Purchase #3	$40.55	11.756%	$45.3171	$45.32	$45.30	$45.30
Purchase #4	$39.81	13.504%	$45.1859	$45.19	$45.20	$45.20
Purchase #5	$148.39	3.212%	$153.1563	$153.16	$153.15	$153.20
Purchase #6	$74.79	4.420%	$78.0957	$78.10	$78.10	$78.10
Purchase #7	$72.83	11.855%	$81.464	$81.46	$81.45	$81.50
7 purchase totals =	$674.80		$729.9390	$729.95	$729.90	$730.00