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	$244.69	7.742%	$263.6339	$263.63	$263.65	$263.60
Purchase #2	$90.44	7.377%	$97.1118	$97.11	$97.10	$97.10
Purchase #3	$92.43	3.301%	$95.4811	$95.48	$95.50	$95.50
Purchase #4	$17.59	3.146%	$18.1434	$18.14	$18.15	$18.10
Purchase #5	$119.71	9.551%	$131.1435	$131.14	$131.15	$131.10
Purchase #6	$12.79	10.783%	$14.1691	$14.17	$14.15	$14.20
Purchase #7	$104.61	7.383%	$112.3334	$112.33	$112.35	$112.30
7 purchase totals =	$682.26		$732.0162	$732.00	$732.05	$731.90