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	$223.33	6.783%	$238.4785	$238.48	$238.50	$238.50
Purchase #2	$85.79	10.182%	$94.5251	$94.53	$94.55	$94.50
Purchase #3	$205.56	4.503%	$214.8164	$214.82	$214.80	$214.80
Purchase #4	$50.90	11.482%	$56.7443	$56.74	$56.75	$56.70
Purchase #5	$139.78	6.106%	$148.315	$148.32	$148.30	$148.30
Purchase #6	$129.89	3.613%	$134.5829	$134.58	$134.60	$134.60
Purchase #7	$209.43	6.804%	$223.6796	$223.68	$223.70	$223.70
7 purchase totals =	$1,044.68		$1,111.1418	$1,111.15	$1,111.20	$1,111.10