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	$116.80	7.700%	$125.7936	$125.79	$125.80	$125.80
Purchase #2	$144.37	9.714%	$158.3941	$158.39	$158.40	$158.40
Purchase #3	$66.29	9.543%	$72.6161	$72.62	$72.60	$72.60
Purchase #4	$189.58	13.284%	$214.7638	$214.76	$214.75	$214.80
Purchase #5	$219.50	6.198%	$233.1046	$233.10	$233.10	$233.10
Purchase #6	$28.43	13.380%	$32.2339	$32.23	$32.25	$32.20
Purchase #7	$101.50	9.699%	$111.3445	$111.34	$111.35	$111.30
7 purchase totals =	$866.47		$948.2506	$948.23	$948.25	$948.20