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	$102.81	6.656%	$109.653	$109.65	$109.65	$109.70
Purchase #2	$204.71	5.104%	$215.1584	$215.16	$215.15	$215.20
Purchase #3	$82.58	4.570%	$86.3539	$86.35	$86.35	$86.40
Purchase #4	$214.60	3.587%	$222.2977	$222.30	$222.30	$222.30
Purchase #5	$218.45	5.343%	$230.1218	$230.12	$230.10	$230.10
Purchase #6	$170.62	10.518%	$188.5658	$188.57	$188.55	$188.60
Purchase #7	$48.65	10.820%	$53.9139	$53.91	$53.90	$53.90
7 purchase totals =	$1,042.42		$1,106.0645	$1,106.06	$1,106.00	$1,106.20