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	$126.61	3.236%	$130.7071	$130.71	$130.70	$130.70
Purchase #2	$61.41	6.485%	$65.3924	$65.39	$65.40	$65.40
Purchase #3	$68.87	13.474%	$78.1495	$78.15	$78.15	$78.10
Purchase #4	$116.47	9.846%	$127.9376	$127.94	$127.95	$127.90
Purchase #5	$160.95	3.621%	$166.778	$166.78	$166.80	$166.80
Purchase #6	$102.27	12.532%	$115.0865	$115.09	$115.10	$115.10
Purchase #7	$43.69	12.818%	$49.2902	$49.29	$49.30	$49.30
7 purchase totals =	$680.27		$733.3413	$733.35	$733.40	$733.30