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	$209.61	12.337%	$235.4696	$235.47	$235.45	$235.50
Purchase #2	$197.37	13.437%	$223.8906	$223.89	$223.90	$223.90
Purchase #3	$183.86	5.687%	$194.3161	$194.32	$194.30	$194.30
Purchase #4	$157.90	4.522%	$165.0402	$165.04	$165.05	$165.00
Purchase #5	$112.79	3.622%	$116.8753	$116.88	$116.90	$116.90
Purchase #6	$151.91	4.379%	$158.5621	$158.56	$158.55	$158.60
Purchase #7	$82.34	5.589%	$86.942	$86.94	$86.95	$86.90
7 purchase totals =	$1,095.78		$1,181.0959	$1,181.10	$1,181.10	$1,181.10