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	$172.48	10.765%	$191.0475	$191.05	$191.05	$191.00
Purchase #2	$44.79	13.582%	$50.8734	$50.87	$50.85	$50.90
Purchase #3	$114.87	13.586%	$130.4762	$130.48	$130.50	$130.50
Purchase #4	$155.31	11.476%	$173.1334	$173.13	$173.15	$173.10
Purchase #5	$186.69	6.625%	$199.0582	$199.06	$199.05	$199.10
Purchase #6	$210.72	5.158%	$221.5889	$221.59	$221.60	$221.60
Purchase #7	$55.96	13.178%	$63.3344	$63.33	$63.35	$63.30
7 purchase totals =	$940.82		$1,029.5120	$1,029.51	$1,029.55	$1,029.50