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	$83.93	10.423%	$92.678	$92.68	$92.70	$92.70
Purchase #2	$118.29	11.869%	$132.3298	$132.33	$132.35	$132.30
Purchase #3	$223.94	3.431%	$231.6234	$231.62	$231.60	$231.60
Purchase #4	$61.51	5.279%	$64.7571	$64.76	$64.75	$64.80
Purchase #5	$149.58	3.600%	$154.9649	$154.96	$154.95	$155.00
Purchase #6	$162.51	7.394%	$174.526	$174.53	$174.55	$174.50
Purchase #7	$151.83	13.540%	$172.3878	$172.39	$172.40	$172.40
7 purchase totals =	$951.59		$1,023.2670	$1,023.27	$1,023.30	$1,023.30