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	$152.73	6.671%	$162.9186	$162.92	$162.90	$162.90
Purchase #2	$9.37	7.440%	$10.0671	$10.07	$10.05	$10.10
Purchase #3	$160.93	10.848%	$178.3877	$178.39	$178.40	$178.40
Purchase #4	$104.85	4.466%	$109.5326	$109.53	$109.55	$109.50
Purchase #5	$78.63	13.543%	$89.2789	$89.28	$89.30	$89.30
Purchase #6	$154.68	3.511%	$160.1108	$160.11	$160.10	$160.10
Purchase #7	$238.82	6.704%	$254.8305	$254.83	$254.85	$254.80
7 purchase totals =	$900.01		$965.1262	$965.13	$965.15	$965.10