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	$204.56	6.495%	$217.8462	$217.85	$217.85	$217.80
Purchase #2	$219.73	13.374%	$249.1167	$249.12	$249.10	$249.10
Purchase #3	$56.58	6.298%	$60.1434	$60.14	$60.15	$60.10
Purchase #4	$114.74	10.773%	$127.1009	$127.10	$127.10	$127.10
Purchase #5	$107.87	5.520%	$113.8244	$113.82	$113.80	$113.80
Purchase #6	$121.26	11.166%	$134.7999	$134.80	$134.80	$134.80
Purchase #7	$118.75	3.627%	$123.0571	$123.06	$123.05	$123.10
7 purchase totals =	$943.49		$1,025.8886	$1,025.89	$1,025.85	$1,025.80