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	$182.81	4.178%	$190.4478	$190.45	$190.45	$190.40
Purchase #2	$77.91	13.129%	$88.1388	$88.14	$88.15	$88.10
Purchase #3	$82.60	3.401%	$85.4092	$85.41	$85.40	$85.40
Purchase #4	$85.86	7.152%	$92.0007	$92.00	$92.00	$92.00
Purchase #5	$141.36	3.745%	$146.6539	$146.65	$146.65	$146.70
Purchase #6	$52.67	4.241%	$54.9037	$54.90	$54.90	$54.90
Purchase #7	$191.98	6.408%	$204.2821	$204.28	$204.30	$204.30
7 purchase totals =	$815.19		$861.8362	$861.83	$861.85	$861.80