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	$57.66	7.428%	$61.943	$61.94	$61.95	$61.90
Purchase #2	$103.49	6.574%	$110.2934	$110.29	$110.30	$110.30
Purchase #3	$244.86	13.718%	$278.4499	$278.45	$278.45	$278.40
Purchase #4	$154.92	7.128%	$165.9627	$165.96	$165.95	$166.00
Purchase #5	$193.32	3.830%	$200.7242	$200.72	$200.70	$200.70
Purchase #6	$130.31	10.643%	$144.1789	$144.18	$144.20	$144.20
Purchase #7	$58.57	10.731%	$64.8551	$64.86	$64.85	$64.90
7 purchase totals =	$943.13		$1,026.4072	$1,026.40	$1,026.40	$1,026.40