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	$212.98	9.467%	$233.1428	$233.14	$233.15	$233.10
Purchase #2	$117.57	11.348%	$130.9118	$130.91	$130.90	$130.90
Purchase #3	$159.47	7.303%	$171.1161	$171.12	$171.10	$171.10
Purchase #4	$239.82	5.271%	$252.4609	$252.46	$252.45	$252.50
Purchase #5	$93.71	8.446%	$101.6247	$101.62	$101.60	$101.60
Purchase #6	$96.55	8.817%	$105.0628	$105.06	$105.05	$105.10
Purchase #7	$181.25	13.642%	$205.9761	$205.98	$206.00	$206.00
7 purchase totals =	$1,101.35		$1,200.2952	$1,200.29	$1,200.25	$1,200.30