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	$216.96	6.525%	$231.1166	$231.12	$231.10	$231.10
Purchase #2	$155.86	5.585%	$164.5648	$164.56	$164.55	$164.60
Purchase #3	$224.77	6.254%	$238.8271	$238.83	$238.85	$238.80
Purchase #4	$72.69	10.317%	$80.1894	$80.19	$80.20	$80.20
Purchase #5	$219.56	12.138%	$246.2102	$246.21	$246.20	$246.20
Purchase #6	$111.94	3.873%	$116.2754	$116.28	$116.30	$116.30
Purchase #7	$45.51	7.290%	$48.8277	$48.83	$48.85	$48.80
7 purchase totals =	$1,047.29		$1,126.0112	$1,126.02	$1,126.05	$1,126.00