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	$161.35	7.675%	$173.7336	$173.73	$173.75	$173.70
Purchase #2	$59.98	3.289%	$61.9527	$61.95	$61.95	$62.00
Purchase #3	$34.72	8.541%	$37.6854	$37.69	$37.70	$37.70
Purchase #4	$49.96	7.663%	$53.7884	$53.79	$53.80	$53.80
Purchase #5	$231.88	13.610%	$263.4389	$263.44	$263.45	$263.40
Purchase #6	$85.95	4.694%	$89.9845	$89.98	$90.00	$90.00
Purchase #7	$36.53	4.298%	$38.1001	$38.10	$38.10	$38.10
7 purchase totals =	$660.37		$718.6836	$718.68	$718.75	$718.70