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	$114.28	10.494%	$126.2725	$126.27	$126.25	$126.30
Purchase #2	$129.59	12.212%	$145.4155	$145.42	$145.40	$145.40
Purchase #3	$143.79	8.117%	$155.4614	$155.46	$155.45	$155.50
Purchase #4	$199.26	7.661%	$214.5253	$214.53	$214.55	$214.50
Purchase #5	$110.73	11.200%	$123.1318	$123.13	$123.15	$123.10
Purchase #6	$93.70	12.131%	$105.0667	$105.07	$105.05	$105.10
Purchase #7	$229.50	5.384%	$241.8563	$241.86	$241.85	$241.90
7 purchase totals =	$1,020.85		$1,111.7295	$1,111.74	$1,111.70	$1,111.80