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	$215.28	6.355%	$228.961	$228.96	$228.95	$229.00
Purchase #2	$56.89	7.428%	$61.1158	$61.12	$61.10	$61.10
Purchase #3	$148.63	11.501%	$165.7239	$165.72	$165.70	$165.70
Purchase #4	$159.88	10.302%	$176.3508	$176.35	$176.35	$176.40
Purchase #5	$11.82	4.510%	$12.3531	$12.35	$12.35	$12.40
Purchase #6	$245.32	5.810%	$259.5731	$259.57	$259.55	$259.60
Purchase #7	$115.57	10.595%	$127.8146	$127.81	$127.80	$127.80
7 purchase totals =	$953.39		$1,031.8923	$1,031.88	$1,031.80	$1,032.00