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	$57.61	9.606%	$63.144	$63.14	$63.15	$63.10
Purchase #2	$68.93	13.624%	$78.321	$78.32	$78.30	$78.30
Purchase #3	$183.52	4.432%	$191.6536	$191.65	$191.65	$191.70
Purchase #4	$155.74	4.470%	$162.7016	$162.70	$162.70	$162.70
Purchase #5	$190.59	10.450%	$210.5067	$210.51	$210.50	$210.50
Purchase #6	$122.41	4.411%	$127.8095	$127.81	$127.80	$127.80
Purchase #7	$195.43	7.472%	$210.0325	$210.03	$210.05	$210.00
7 purchase totals =	$974.23		$1,044.1689	$1,044.16	$1,044.15	$1,044.10