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	$60.60	8.731%	$65.891	$65.89	$65.90	$65.90
Purchase #2	$158.62	9.286%	$173.3495	$173.35	$173.35	$173.30
Purchase #3	$101.34	8.723%	$110.1799	$110.18	$110.20	$110.20
Purchase #4	$216.33	6.129%	$229.5889	$229.59	$229.60	$229.60
Purchase #5	$148.43	12.733%	$167.3296	$167.33	$167.35	$167.30
Purchase #6	$139.52	12.172%	$156.5024	$156.50	$156.50	$156.50
Purchase #7	$98.97	12.397%	$111.2393	$111.24	$111.25	$111.20
7 purchase totals =	$923.81		$1,014.0806	$1,014.08	$1,014.15	$1,014.00