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	$211.41	5.420%	$222.8684	$222.87	$222.85	$222.90
Purchase #2	$233.85	8.327%	$253.3227	$253.32	$253.30	$253.30
Purchase #3	$163.32	5.836%	$172.8514	$172.85	$172.85	$172.90
Purchase #4	$76.65	11.744%	$85.6518	$85.65	$85.65	$85.70
Purchase #5	$131.72	7.147%	$141.134	$141.13	$141.15	$141.10
Purchase #6	$110.58	12.793%	$124.7265	$124.73	$124.75	$124.70
Purchase #7	$126.76	12.547%	$142.6646	$142.66	$142.65	$142.70
7 purchase totals =	$1,054.29		$1,143.2194	$1,143.21	$1,143.20	$1,143.30