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	$211.73	10.428%	$233.8092	$233.81	$233.80	$233.80
Purchase #2	$59.46	10.302%	$65.5856	$65.59	$65.60	$65.60
Purchase #3	$204.59	3.295%	$211.3312	$211.33	$211.35	$211.30
Purchase #4	$106.45	8.676%	$115.6856	$115.69	$115.70	$115.70
Purchase #5	$102.33	10.114%	$112.6797	$112.68	$112.70	$112.70
Purchase #6	$148.85	6.261%	$158.1695	$158.17	$158.15	$158.20
Purchase #7	$147.78	11.108%	$164.1954	$164.20	$164.20	$164.20
7 purchase totals =	$981.19		$1,061.4562	$1,061.47	$1,061.50	$1,061.50