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	$94.56	9.679%	$103.7125	$103.71	$103.70	$103.70
Purchase #2	$190.87	7.543%	$205.2673	$205.27	$205.25	$205.30
Purchase #3	$219.63	7.316%	$235.6981	$235.70	$235.70	$235.70
Purchase #4	$145.40	10.180%	$160.2017	$160.20	$160.20	$160.20
Purchase #5	$79.93	13.191%	$90.4736	$90.47	$90.45	$90.50
Purchase #6	$134.30	13.858%	$152.9113	$152.91	$152.90	$152.90
Purchase #7	$207.72	3.312%	$214.5997	$214.60	$214.60	$214.60
7 purchase totals =	$1,072.41		$1,162.8642	$1,162.86	$1,162.80	$1,162.90