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	$206.48	4.465%	$215.6993	$215.70	$215.70	$215.70
Purchase #2	$61.62	6.312%	$65.5095	$65.51	$65.50	$65.50
Purchase #3	$99.32	4.176%	$103.4676	$103.47	$103.45	$103.50
Purchase #4	$240.28	11.129%	$267.0208	$267.02	$267.00	$267.00
Purchase #5	$167.51	4.745%	$175.4583	$175.46	$175.45	$175.50
Purchase #6	$212.35	3.346%	$219.4552	$219.46	$219.45	$219.50
Purchase #7	$27.92	4.363%	$29.1381	$29.14	$29.15	$29.10
7 purchase totals =	$1,015.48		$1,075.7488	$1,075.76	$1,075.70	$1,075.80