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	$196.26	9.478%	$214.8615	$214.86	$214.85	$214.90
Purchase #2	$92.53	7.298%	$99.2828	$99.28	$99.30	$99.30
Purchase #3	$46.44	10.571%	$51.3492	$51.35	$51.35	$51.30
Purchase #4	$16.38	11.706%	$18.2974	$18.30	$18.30	$18.30
Purchase #5	$143.82	6.597%	$153.3078	$153.31	$153.30	$153.30
Purchase #6	$49.27	4.309%	$51.393	$51.39	$51.40	$51.40
Purchase #7	$158.60	9.787%	$174.1222	$174.12	$174.10	$174.10
7 purchase totals =	$703.30		$762.6139	$762.61	$762.60	$762.60