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	$231.75	5.818%	$245.2332	$245.23	$245.25	$245.20
Purchase #2	$164.65	4.652%	$172.3095	$172.31	$172.30	$172.30
Purchase #3	$12.98	4.532%	$13.5683	$13.57	$13.55	$13.60
Purchase #4	$172.55	4.460%	$180.2457	$180.25	$180.25	$180.20
Purchase #5	$183.72	11.455%	$204.7651	$204.77	$204.75	$204.80
Purchase #6	$169.57	13.739%	$192.8672	$192.87	$192.85	$192.90
Purchase #7	$165.51	6.431%	$176.1539	$176.15	$176.15	$176.20
7 purchase totals =	$1,100.73		$1,185.1429	$1,185.15	$1,185.10	$1,185.20