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	$146.34	4.585%	$153.0497	$153.05	$153.05	$153.00
Purchase #2	$185.33	11.338%	$206.3427	$206.34	$206.35	$206.30
Purchase #3	$187.45	11.346%	$208.7181	$208.72	$208.70	$208.70
Purchase #4	$226.37	3.671%	$234.68	$234.68	$234.70	$234.70
Purchase #5	$37.28	6.473%	$39.6931	$39.69	$39.70	$39.70
Purchase #6	$131.49	11.770%	$146.9664	$146.97	$146.95	$147.00
Purchase #7	$65.25	10.536%	$72.1247	$72.12	$72.10	$72.10
7 purchase totals =	$979.51		$1,061.5747	$1,061.57	$1,061.55	$1,061.50