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	$153.88	5.618%	$162.525	$162.53	$162.55	$162.50
Purchase #2	$29.72	8.255%	$32.1734	$32.17	$32.15	$32.20
Purchase #3	$61.56	13.131%	$69.6434	$69.64	$69.65	$69.60
Purchase #4	$65.88	11.330%	$73.3442	$73.34	$73.35	$73.30
Purchase #5	$94.36	6.709%	$100.6906	$100.69	$100.70	$100.70
Purchase #6	$78.26	13.854%	$89.1021	$89.10	$89.10	$89.10
Purchase #7	$53.71	9.577%	$58.8538	$58.85	$58.85	$58.90
7 purchase totals =	$537.37		$586.3325	$586.32	$586.35	$586.30