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	$102.71	8.490%	$111.4301	$111.43	$111.45	$111.40
Purchase #2	$164.68	8.117%	$178.0471	$178.05	$178.05	$178.00
Purchase #3	$161.47	11.719%	$180.3927	$180.39	$180.40	$180.40
Purchase #4	$154.31	7.390%	$165.7135	$165.71	$165.70	$165.70
Purchase #5	$191.98	4.615%	$200.8399	$200.84	$200.85	$200.80
Purchase #6	$28.87	12.351%	$32.4357	$32.44	$32.45	$32.40
Purchase #7	$158.99	12.424%	$178.7429	$178.74	$178.75	$178.70
7 purchase totals =	$963.01		$1,047.6019	$1,047.60	$1,047.65	$1,047.40