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	$168.84	3.400%	$174.5806	$174.58	$174.60	$174.60
Purchase #2	$114.33	3.332%	$118.1395	$118.14	$118.15	$118.10
Purchase #3	$148.27	7.153%	$158.8758	$158.88	$158.90	$158.90
Purchase #4	$65.34	3.255%	$67.4668	$67.47	$67.45	$67.50
Purchase #5	$114.35	13.528%	$129.8193	$129.82	$129.80	$129.80
Purchase #6	$167.85	3.161%	$173.1557	$173.16	$173.15	$173.20
Purchase #7	$116.59	11.825%	$130.3768	$130.38	$130.40	$130.40
7 purchase totals =	$895.57		$952.4145	$952.43	$952.45	$952.50