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	$175.58	11.136%	$195.1326	$195.13	$195.15	$195.10
Purchase #2	$112.88	9.108%	$123.1611	$123.16	$123.15	$123.20
Purchase #3	$172.25	6.589%	$183.5996	$183.60	$183.60	$183.60
Purchase #4	$153.33	9.633%	$168.1003	$168.10	$168.10	$168.10
Purchase #5	$166.54	11.473%	$185.6471	$185.65	$185.65	$185.60
Purchase #6	$165.50	12.800%	$186.684	$186.68	$186.70	$186.70
Purchase #7	$153.60	13.224%	$173.9121	$173.91	$173.90	$173.90
7 purchase totals =	$1,099.68		$1,216.2368	$1,216.23	$1,216.25	$1,216.20