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	$101.50	9.492%	$111.1344	$111.13	$111.15	$111.10
Purchase #2	$57.25	9.183%	$62.5073	$62.51	$62.50	$62.50
Purchase #3	$242.32	7.148%	$259.641	$259.64	$259.65	$259.60
Purchase #4	$138.41	11.667%	$154.5583	$154.56	$154.55	$154.60
Purchase #5	$152.84	13.499%	$173.4719	$173.47	$173.45	$173.50
Purchase #6	$168.70	10.575%	$186.54	$186.54	$186.55	$186.50
Purchase #7	$184.40	7.459%	$198.1544	$198.15	$198.15	$198.20
7 purchase totals =	$1,045.42		$1,146.0073	$1,146.00	$1,146.00	$1,146.00