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	$94.62	9.553%	$103.659	$103.66	$103.65	$103.70
Purchase #2	$72.67	8.196%	$78.626	$78.63	$78.65	$78.60
Purchase #3	$233.29	11.415%	$259.9201	$259.92	$259.90	$259.90
Purchase #4	$127.46	12.431%	$143.3046	$143.30	$143.30	$143.30
Purchase #5	$117.71	6.742%	$125.646	$125.65	$125.65	$125.60
Purchase #6	$115.98	6.414%	$123.419	$123.42	$123.40	$123.40
Purchase #7	$96.89	9.562%	$106.1546	$106.15	$106.15	$106.20
7 purchase totals =	$858.62		$940.7293	$940.73	$940.70	$940.70