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	$118.81	7.666%	$127.918	$127.92	$127.90	$127.90
Purchase #2	$41.78	8.272%	$45.236	$45.24	$45.25	$45.20
Purchase #3	$232.86	10.243%	$256.7118	$256.71	$256.70	$256.70
Purchase #4	$35.91	9.204%	$39.2152	$39.22	$39.20	$39.20
Purchase #5	$117.85	5.717%	$124.5875	$124.59	$124.60	$124.60
Purchase #6	$164.74	6.817%	$175.9703	$175.97	$175.95	$176.00
Purchase #7	$241.59	9.154%	$263.7051	$263.71	$263.70	$263.70
7 purchase totals =	$953.54		$1,033.3439	$1,033.36	$1,033.30	$1,033.30