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	$208.48	6.801%	$222.6587	$222.66	$222.65	$222.70
Purchase #2	$213.51	8.707%	$232.1003	$232.10	$232.10	$232.10
Purchase #3	$40.88	3.381%	$42.2622	$42.26	$42.25	$42.30
Purchase #4	$95.85	10.454%	$105.8702	$105.87	$105.85	$105.90
Purchase #5	$26.30	12.753%	$29.654	$29.65	$29.65	$29.70
Purchase #6	$248.54	4.320%	$259.2769	$259.28	$259.30	$259.30
Purchase #7	$179.30	7.354%	$192.4857	$192.49	$192.50	$192.50
7 purchase totals =	$1,012.86		$1,084.3080	$1,084.31	$1,084.30	$1,084.50