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	$190.50	3.144%	$196.4893	$196.49	$196.50	$196.50
Purchase #2	$95.46	4.665%	$99.9132	$99.91	$99.90	$99.90
Purchase #3	$11.80	11.182%	$13.1195	$13.12	$13.10	$13.10
Purchase #4	$104.66	11.497%	$116.6928	$116.69	$116.70	$116.70
Purchase #5	$191.33	7.221%	$205.1459	$205.15	$205.15	$205.10
Purchase #6	$250.62	3.374%	$259.0759	$259.08	$259.10	$259.10
Purchase #7	$223.30	13.572%	$253.6063	$253.61	$253.60	$253.60
7 purchase totals =	$1,067.67		$1,144.0429	$1,144.05	$1,144.05	$1,144.00