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	$149.83	5.670%	$158.3254	$158.33	$158.35	$158.30
Purchase #2	$188.52	11.662%	$210.5052	$210.51	$210.50	$210.50
Purchase #3	$75.60	13.375%	$85.7115	$85.71	$85.70	$85.70
Purchase #4	$9.65	8.574%	$10.4774	$10.48	$10.50	$10.50
Purchase #5	$164.28	9.647%	$180.1281	$180.13	$180.15	$180.10
Purchase #6	$90.53	4.233%	$94.3621	$94.36	$94.35	$94.40
Purchase #7	$248.32	13.812%	$282.618	$282.62	$282.60	$282.60
7 purchase totals =	$926.73		$1,022.1277	$1,022.14	$1,022.15	$1,022.10