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	$149.43	10.833%	$165.6178	$165.62	$165.60	$165.60
Purchase #2	$28.31	12.778%	$31.9275	$31.93	$31.95	$31.90
Purchase #3	$86.85	8.537%	$94.2644	$94.26	$94.25	$94.30
Purchase #4	$224.34	10.501%	$247.8979	$247.90	$247.90	$247.90
Purchase #5	$233.86	13.137%	$264.5822	$264.58	$264.60	$264.60
Purchase #6	$37.41	8.442%	$40.5682	$40.57	$40.55	$40.60
Purchase #7	$210.74	3.250%	$217.5891	$217.59	$217.60	$217.60
7 purchase totals =	$970.94		$1,062.4471	$1,062.45	$1,062.45	$1,062.50