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	$213.33	4.843%	$223.6616	$223.66	$223.65	$223.70
Purchase #2	$57.51	11.190%	$63.9454	$63.95	$63.95	$63.90
Purchase #3	$151.66	13.574%	$172.2463	$172.25	$172.25	$172.20
Purchase #4	$197.85	13.333%	$224.2293	$224.23	$224.25	$224.20
Purchase #5	$127.63	5.102%	$134.1417	$134.14	$134.15	$134.10
Purchase #6	$40.61	5.784%	$42.9589	$42.96	$42.95	$43.00
Purchase #7	$162.38	11.858%	$181.635	$181.64	$181.65	$181.60
7 purchase totals =	$950.97		$1,042.8182	$1,042.83	$1,042.85	$1,042.70