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	$85.47	13.465%	$96.9785	$96.98	$97.00	$97.00
Purchase #2	$144.50	12.139%	$162.0409	$162.04	$162.05	$162.00
Purchase #3	$53.98	3.130%	$55.6696	$55.67	$55.65	$55.70
Purchase #4	$247.98	3.304%	$256.1733	$256.17	$256.15	$256.20
Purchase #5	$80.93	7.274%	$86.8168	$86.82	$86.80	$86.80
Purchase #6	$11.68	6.287%	$12.4143	$12.41	$12.40	$12.40
Purchase #7	$54.38	8.157%	$58.8158	$58.82	$58.80	$58.80
7 purchase totals =	$678.92		$728.9092	$728.91	$728.85	$728.90