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	$94.48	9.644%	$103.5917	$103.59	$103.60	$103.60
Purchase #2	$249.42	4.305%	$260.1575	$260.16	$260.15	$260.20
Purchase #3	$50.88	4.358%	$53.0974	$53.10	$53.10	$53.10
Purchase #4	$31.59	5.428%	$33.3047	$33.30	$33.30	$33.30
Purchase #5	$240.58	11.490%	$268.2226	$268.22	$268.20	$268.20
Purchase #6	$189.99	11.829%	$212.4639	$212.46	$212.45	$212.50
Purchase #7	$76.45	12.607%	$86.0881	$86.09	$86.10	$86.10
7 purchase totals =	$933.39		$1,016.9259	$1,016.92	$1,016.90	$1,017.00