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	$112.61	9.551%	$123.3654	$123.37	$123.35	$123.40
Purchase #2	$94.72	6.687%	$101.0539	$101.05	$101.05	$101.10
Purchase #3	$161.56	6.842%	$172.6139	$172.61	$172.60	$172.60
Purchase #4	$106.34	5.132%	$111.7974	$111.80	$111.80	$111.80
Purchase #5	$90.27	10.151%	$99.4333	$99.43	$99.45	$99.40
Purchase #6	$188.74	13.543%	$214.3011	$214.30	$214.30	$214.30
Purchase #7	$187.39	8.621%	$203.5449	$203.54	$203.55	$203.50
7 purchase totals =	$941.63		$1,026.1099	$1,026.10	$1,026.10	$1,026.10