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	$59.64	4.631%	$62.4019	$62.40	$62.40	$62.40
Purchase #2	$32.53	10.215%	$35.8529	$35.85	$35.85	$35.90
Purchase #3	$218.38	10.500%	$241.3099	$241.31	$241.30	$241.30
Purchase #4	$147.34	8.170%	$159.3777	$159.38	$159.40	$159.40
Purchase #5	$205.97	13.198%	$233.1539	$233.15	$233.15	$233.20
Purchase #6	$248.75	8.352%	$269.5256	$269.53	$269.55	$269.50
Purchase #7	$170.80	5.332%	$179.9071	$179.91	$179.90	$179.90
7 purchase totals =	$1,083.41		$1,181.5290	$1,181.53	$1,181.55	$1,181.60