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	$245.78	8.152%	$265.816	$265.82	$265.80	$265.80
Purchase #2	$78.49	5.538%	$82.8368	$82.84	$82.85	$82.80
Purchase #3	$238.47	12.772%	$268.9274	$268.93	$268.95	$268.90
Purchase #4	$18.41	6.797%	$19.6613	$19.66	$19.65	$19.70
Purchase #5	$55.95	9.527%	$61.2804	$61.28	$61.30	$61.30
Purchase #6	$142.49	7.478%	$153.1454	$153.15	$153.15	$153.10
Purchase #7	$172.65	7.565%	$185.711	$185.71	$185.70	$185.70
7 purchase totals =	$952.24		$1,037.3783	$1,037.39	$1,037.40	$1,037.30