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	$174.90	4.374%	$182.5501	$182.55	$182.55	$182.60
Purchase #2	$212.30	4.608%	$222.0828	$222.08	$222.10	$222.10
Purchase #3	$183.32	4.497%	$191.5639	$191.56	$191.55	$191.60
Purchase #4	$48.81	11.205%	$54.2792	$54.28	$54.30	$54.30
Purchase #5	$147.44	8.233%	$159.5787	$159.58	$159.60	$159.60
Purchase #6	$227.30	3.129%	$234.4122	$234.41	$234.40	$234.40
Purchase #7	$115.67	13.646%	$131.4543	$131.45	$131.45	$131.50
7 purchase totals =	$1,109.74		$1,175.9212	$1,175.91	$1,175.95	$1,176.10