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	$95.77	12.715%	$107.9472	$107.95	$107.95	$107.90
Purchase #2	$6.48	12.625%	$7.2981	$7.30	$7.30	$7.30
Purchase #3	$91.28	3.298%	$94.2904	$94.29	$94.30	$94.30
Purchase #4	$116.75	9.457%	$127.791	$127.79	$127.80	$127.80
Purchase #5	$191.68	3.385%	$198.1684	$198.17	$198.15	$198.20
Purchase #6	$83.52	9.440%	$91.4043	$91.40	$91.40	$91.40
Purchase #7	$99.75	3.859%	$103.5994	$103.60	$103.60	$103.60
7 purchase totals =	$685.23		$730.4988	$730.50	$730.50	$730.50