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	$38.83	3.557%	$40.2112	$40.21	$40.20	$40.20
Purchase #2	$9.53	5.483%	$10.0525	$10.05	$10.05	$10.10
Purchase #3	$175.84	11.755%	$196.51	$196.51	$196.50	$196.50
Purchase #4	$126.62	3.416%	$130.9453	$130.95	$130.95	$130.90
Purchase #5	$180.55	3.661%	$187.1599	$187.16	$187.15	$187.20
Purchase #6	$180.31	6.348%	$191.7561	$191.76	$191.75	$191.80
Purchase #7	$192.58	10.563%	$212.9222	$212.92	$212.90	$212.90
7 purchase totals =	$904.26		$969.5572	$969.56	$969.50	$969.60