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	$161.76	3.575%	$167.5429	$167.54	$167.55	$167.50
Purchase #2	$5.43	13.505%	$6.1633	$6.16	$6.15	$6.20
Purchase #3	$95.84	4.421%	$100.0771	$100.08	$100.10	$100.10
Purchase #4	$169.47	7.325%	$181.8837	$181.88	$181.90	$181.90
Purchase #5	$244.73	6.802%	$261.3765	$261.38	$261.40	$261.40
Purchase #6	$53.48	11.292%	$59.519	$59.52	$59.50	$59.50
Purchase #7	$67.60	13.422%	$76.6733	$76.67	$76.65	$76.70
7 purchase totals =	$798.31		$853.2358	$853.23	$853.25	$853.30