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	$152.64	13.787%	$173.6845	$173.68	$173.70	$173.70
Purchase #2	$153.31	13.253%	$173.6282	$173.63	$173.65	$173.60
Purchase #3	$162.84	7.741%	$175.4454	$175.45	$175.45	$175.40
Purchase #4	$237.73	12.666%	$267.8409	$267.84	$267.85	$267.80
Purchase #5	$89.44	6.675%	$95.4101	$95.41	$95.40	$95.40
Purchase #6	$105.37	5.511%	$111.1769	$111.18	$111.20	$111.20
Purchase #7	$16.54	13.449%	$18.7645	$18.76	$18.75	$18.80
7 purchase totals =	$917.87		$1,015.9505	$1,015.95	$1,016.00	$1,015.90