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	$137.85	10.176%	$151.8776	$151.88	$151.90	$151.90
Purchase #2	$164.79	5.773%	$174.3033	$174.30	$174.30	$174.30
Purchase #3	$149.87	5.495%	$158.1054	$158.11	$158.10	$158.10
Purchase #4	$217.40	5.223%	$228.7548	$228.75	$228.75	$228.80
Purchase #5	$56.89	10.393%	$62.8026	$62.80	$62.80	$62.80
Purchase #6	$210.50	6.374%	$223.9173	$223.92	$223.90	$223.90
Purchase #7	$85.89	9.742%	$94.2574	$94.26	$94.25	$94.30
7 purchase totals =	$1,023.19		$1,094.0184	$1,094.02	$1,094.00	$1,094.10