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	$232.67	5.698%	$245.9275	$245.93	$245.95	$245.90
Purchase #2	$226.61	11.621%	$252.9443	$252.94	$252.95	$252.90
Purchase #3	$103.95	7.710%	$111.9645	$111.96	$111.95	$112.00
Purchase #4	$148.33	3.109%	$152.9416	$152.94	$152.95	$152.90
Purchase #5	$137.32	5.728%	$145.1857	$145.19	$145.20	$145.20
Purchase #6	$134.74	11.749%	$150.5706	$150.57	$150.55	$150.60
Purchase #7	$52.71	4.595%	$55.132	$55.13	$55.15	$55.10
7 purchase totals =	$1,036.33		$1,114.6662	$1,114.66	$1,114.70	$1,114.60