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	$244.42	3.116%	$252.0361	$252.04	$252.05	$252.00
Purchase #2	$102.37	6.215%	$108.7323	$108.73	$108.75	$108.70
Purchase #3	$121.66	4.836%	$127.5435	$127.54	$127.55	$127.50
Purchase #4	$176.73	5.192%	$185.9058	$185.91	$185.90	$185.90
Purchase #5	$220.45	11.198%	$245.136	$245.14	$245.15	$245.10
Purchase #6	$93.36	7.459%	$100.3237	$100.32	$100.30	$100.30
Purchase #7	$68.92	12.871%	$77.7907	$77.79	$77.80	$77.80
7 purchase totals =	$1,027.91		$1,097.4681	$1,097.47	$1,097.50	$1,097.30