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	$105.86	8.577%	$114.9396	$114.94	$114.95	$114.90
Purchase #2	$187.96	4.770%	$196.9257	$196.93	$196.95	$196.90
Purchase #3	$212.72	8.123%	$229.9992	$230.00	$230.00	$230.00
Purchase #4	$214.74	13.689%	$244.1358	$244.14	$244.15	$244.10
Purchase #5	$31.47	12.463%	$35.3921	$35.39	$35.40	$35.40
Purchase #6	$115.87	12.333%	$130.1602	$130.16	$130.15	$130.20
Purchase #7	$87.52	3.157%	$90.283	$90.28	$90.30	$90.30
7 purchase totals =	$956.14		$1,041.8356	$1,041.84	$1,041.90	$1,041.80