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	$140.91	8.464%	$152.8366	$152.84	$152.85	$152.80
Purchase #2	$11.73	4.696%	$12.2808	$12.28	$12.30	$12.30
Purchase #3	$215.95	3.104%	$222.6531	$222.65	$222.65	$222.70
Purchase #4	$5.69	8.364%	$6.1659	$6.17	$6.15	$6.20
Purchase #5	$61.83	9.735%	$67.8492	$67.85	$67.85	$67.80
Purchase #6	$210.93	5.435%	$222.394	$222.39	$222.40	$222.40
Purchase #7	$165.75	8.434%	$179.7294	$179.73	$179.75	$179.70
7 purchase totals =	$812.79		$863.9090	$863.91	$863.95	$863.90