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	$130.50	7.319%	$140.0513	$140.05	$140.05	$140.10
Purchase #2	$192.96	6.368%	$205.2477	$205.25	$205.25	$205.20
Purchase #3	$88.82	3.361%	$91.8052	$91.81	$91.80	$91.80
Purchase #4	$181.51	8.186%	$196.3684	$196.37	$196.35	$196.40
Purchase #5	$129.50	10.207%	$142.7181	$142.72	$142.70	$142.70
Purchase #6	$192.87	8.151%	$208.5908	$208.59	$208.60	$208.60
Purchase #7	$114.72	13.629%	$130.3552	$130.36	$130.35	$130.40
7 purchase totals =	$1,030.88		$1,115.1367	$1,115.15	$1,115.10	$1,115.20