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	$114.83	11.174%	$127.6611	$127.66	$127.65	$127.70
Purchase #2	$137.45	3.479%	$142.2319	$142.23	$142.25	$142.20
Purchase #3	$189.30	7.486%	$203.471	$203.47	$203.45	$203.50
Purchase #4	$164.85	5.240%	$173.4881	$173.49	$173.50	$173.50
Purchase #5	$224.54	5.857%	$237.6913	$237.69	$237.70	$237.70
Purchase #6	$54.30	5.650%	$57.368	$57.37	$57.35	$57.40
Purchase #7	$77.35	5.235%	$81.3993	$81.40	$81.40	$81.40
7 purchase totals =	$962.62		$1,023.3107	$1,023.31	$1,023.30	$1,023.40