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	$108.96	4.707%	$114.0887	$114.09	$114.10	$114.10
Purchase #2	$36.28	7.762%	$39.0961	$39.10	$39.10	$39.10
Purchase #3	$230.28	11.453%	$256.654	$256.65	$256.65	$256.70
Purchase #4	$99.93	9.404%	$109.3274	$109.33	$109.35	$109.30
Purchase #5	$56.58	4.714%	$59.2472	$59.25	$59.25	$59.20
Purchase #6	$94.45	7.666%	$101.6905	$101.69	$101.70	$101.70
Purchase #7	$13.65	3.462%	$14.1226	$14.12	$14.10	$14.10
7 purchase totals =	$640.13		$694.2265	$694.23	$694.25	$694.20