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	$111.77	4.586%	$116.8958	$116.90	$116.90	$116.90
Purchase #2	$21.33	3.620%	$22.1021	$22.10	$22.10	$22.10
Purchase #3	$61.28	6.631%	$65.3435	$65.34	$65.35	$65.30
Purchase #4	$89.97	11.817%	$100.6018	$100.60	$100.60	$100.60
Purchase #5	$183.91	5.252%	$193.569	$193.57	$193.55	$193.60
Purchase #6	$140.78	7.599%	$151.4779	$151.48	$151.50	$151.50
Purchase #7	$53.77	6.691%	$57.3678	$57.37	$57.35	$57.40
7 purchase totals =	$662.81		$707.3579	$707.36	$707.35	$707.40