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	$211.80	8.752%	$230.3367	$230.34	$230.35	$230.30
Purchase #2	$241.88	9.667%	$265.2625	$265.26	$265.25	$265.30
Purchase #3	$98.90	5.519%	$104.3583	$104.36	$104.35	$104.40
Purchase #4	$62.29	8.415%	$67.5317	$67.53	$67.55	$67.50
Purchase #5	$165.50	5.172%	$174.0597	$174.06	$174.05	$174.10
Purchase #6	$109.62	12.331%	$123.1372	$123.14	$123.15	$123.10
Purchase #7	$141.32	7.696%	$152.196	$152.20	$152.20	$152.20
7 purchase totals =	$1,031.31		$1,116.8821	$1,116.89	$1,116.90	$1,116.90