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	$124.94	5.375%	$131.6555	$131.66	$131.65	$131.70
Purchase #2	$159.85	13.775%	$181.8693	$181.87	$181.85	$181.90
Purchase #3	$57.34	6.606%	$61.1279	$61.13	$61.15	$61.10
Purchase #4	$42.81	13.836%	$48.7332	$48.73	$48.75	$48.70
Purchase #5	$229.69	8.224%	$248.5797	$248.58	$248.60	$248.60
Purchase #6	$181.28	10.378%	$200.0932	$200.09	$200.10	$200.10
Purchase #7	$218.43	9.152%	$238.4207	$238.42	$238.40	$238.40
7 purchase totals =	$1,014.34		$1,110.4795	$1,110.48	$1,110.50	$1,110.50