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	$114.90	13.755%	$130.7045	$130.70	$130.70	$130.70
Purchase #2	$163.91	9.519%	$179.5126	$179.51	$179.50	$179.50
Purchase #3	$90.34	6.480%	$96.194	$96.19	$96.20	$96.20
Purchase #4	$208.51	5.262%	$219.4818	$219.48	$219.50	$219.50
Purchase #5	$94.66	11.431%	$105.4806	$105.48	$105.50	$105.50
Purchase #6	$48.66	9.183%	$53.1284	$53.13	$53.15	$53.10
Purchase #7	$234.75	11.638%	$262.0702	$262.07	$262.05	$262.10
7 purchase totals =	$955.73		$1,046.5721	$1,046.56	$1,046.60	$1,046.60