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	$205.84	13.388%	$233.3979	$233.40	$233.40	$233.40
Purchase #2	$204.69	3.210%	$211.2605	$211.26	$211.25	$211.30
Purchase #3	$55.69	11.739%	$62.2274	$62.23	$62.25	$62.20
Purchase #4	$148.35	12.499%	$166.8923	$166.89	$166.90	$166.90
Purchase #5	$45.33	12.272%	$50.8929	$50.89	$50.90	$50.90
Purchase #6	$53.42	7.606%	$57.4831	$57.48	$57.50	$57.50
Purchase #7	$207.39	9.152%	$226.3703	$226.37	$226.35	$226.40
7 purchase totals =	$920.71		$1,008.5244	$1,008.52	$1,008.55	$1,008.60