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	$181.80	8.554%	$197.3512	$197.35	$197.35	$197.40
Purchase #2	$166.34	9.117%	$181.5052	$181.51	$181.50	$181.50
Purchase #3	$64.41	3.838%	$66.8821	$66.88	$66.90	$66.90
Purchase #4	$183.38	4.457%	$191.5532	$191.55	$191.55	$191.60
Purchase #5	$189.73	11.449%	$211.4522	$211.45	$211.45	$211.50
Purchase #6	$80.92	10.733%	$89.6051	$89.61	$89.60	$89.60
Purchase #7	$202.34	5.619%	$213.7095	$213.71	$213.70	$213.70
7 purchase totals =	$1,068.92		$1,152.0585	$1,152.06	$1,152.05	$1,152.20