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	$154.53	9.757%	$169.6075	$169.61	$169.60	$169.60
Purchase #2	$162.68	13.499%	$184.6402	$184.64	$184.65	$184.60
Purchase #3	$89.69	5.236%	$94.3862	$94.39	$94.40	$94.40
Purchase #4	$230.46	11.296%	$256.4928	$256.49	$256.50	$256.50
Purchase #5	$69.97	9.495%	$76.6137	$76.61	$76.60	$76.60
Purchase #6	$118.58	7.211%	$127.1308	$127.13	$127.15	$127.10
Purchase #7	$131.28	5.632%	$138.6737	$138.67	$138.65	$138.70
7 purchase totals =	$957.19		$1,047.5449	$1,047.54	$1,047.55	$1,047.50