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	$214.96	3.341%	$222.1418	$222.14	$222.15	$222.10
Purchase #2	$250.62	11.521%	$279.4939	$279.49	$279.50	$279.50
Purchase #3	$211.28	8.767%	$229.8029	$229.80	$229.80	$229.80
Purchase #4	$71.50	9.739%	$78.4634	$78.46	$78.45	$78.50
Purchase #5	$128.92	3.402%	$133.3059	$133.31	$133.30	$133.30
Purchase #6	$37.99	4.567%	$39.725	$39.73	$39.75	$39.70
Purchase #7	$47.89	11.129%	$53.2197	$53.22	$53.20	$53.20
7 purchase totals =	$963.16		$1,036.1526	$1,036.15	$1,036.15	$1,036.10