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	$89.43	8.531%	$97.0593	$97.06	$97.05	$97.10
Purchase #2	$104.69	4.745%	$109.6575	$109.66	$109.65	$109.70
Purchase #3	$25.28	8.530%	$27.4364	$27.44	$27.45	$27.40
Purchase #4	$26.84	4.810%	$28.131	$28.13	$28.15	$28.10
Purchase #5	$10.34	6.647%	$11.0273	$11.03	$11.05	$11.00
Purchase #6	$81.86	10.594%	$90.5322	$90.53	$90.55	$90.50
Purchase #7	$19.30	10.685%	$21.3622	$21.36	$21.35	$21.40
7 purchase totals =	$357.74		$385.2059	$385.21	$385.25	$385.20