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	$55.96	9.468%	$61.2583	$61.26	$61.25	$61.30
Purchase #2	$96.78	3.848%	$100.5041	$100.50	$100.50	$100.50
Purchase #3	$250.47	10.525%	$276.832	$276.83	$276.85	$276.80
Purchase #4	$149.28	7.791%	$160.9104	$160.91	$160.90	$160.90
Purchase #5	$158.56	10.652%	$175.4498	$175.45	$175.45	$175.40
Purchase #6	$184.73	5.730%	$195.315	$195.32	$195.30	$195.30
Purchase #7	$243.60	4.744%	$255.1564	$255.16	$255.15	$255.20
7 purchase totals =	$1,139.38		$1,225.4260	$1,225.43	$1,225.40	$1,225.40