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	$33.94	13.279%	$38.4469	$38.45	$38.45	$38.40
Purchase #2	$247.84	5.870%	$262.3882	$262.39	$262.40	$262.40
Purchase #3	$33.26	11.588%	$37.1142	$37.11	$37.10	$37.10
Purchase #4	$40.41	12.832%	$45.5954	$45.60	$45.60	$45.60
Purchase #5	$222.32	5.513%	$234.5765	$234.58	$234.60	$234.60
Purchase #6	$165.51	13.370%	$187.6387	$187.64	$187.65	$187.60
Purchase #7	$205.83	6.156%	$218.5009	$218.50	$218.50	$218.50
7 purchase totals =	$949.11		$1,024.2608	$1,024.27	$1,024.30	$1,024.20