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	$219.30	8.705%	$238.3901	$238.39	$238.40	$238.40
Purchase #2	$194.78	8.541%	$211.4162	$211.42	$211.40	$211.40
Purchase #3	$50.33	4.203%	$52.4454	$52.45	$52.45	$52.40
Purchase #4	$209.59	11.660%	$234.0282	$234.03	$234.05	$234.00
Purchase #5	$146.70	13.814%	$166.9651	$166.97	$166.95	$167.00
Purchase #6	$98.68	13.162%	$111.6683	$111.67	$111.65	$111.70
Purchase #7	$111.83	5.831%	$118.3508	$118.35	$118.35	$118.40
7 purchase totals =	$1,031.21		$1,133.2641	$1,133.28	$1,133.25	$1,133.30