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	$84.32	13.416%	$95.6324	$95.63	$95.65	$95.60
Purchase #2	$96.60	3.796%	$100.2669	$100.27	$100.25	$100.30
Purchase #3	$137.93	12.760%	$155.5299	$155.53	$155.55	$155.50
Purchase #4	$85.50	4.522%	$89.3663	$89.37	$89.35	$89.40
Purchase #5	$175.60	7.539%	$188.8385	$188.84	$188.85	$188.80
Purchase #6	$124.61	10.516%	$137.714	$137.71	$137.70	$137.70
Purchase #7	$241.56	3.560%	$250.1595	$250.16	$250.15	$250.20
7 purchase totals =	$946.12		$1,017.5075	$1,017.51	$1,017.50	$1,017.50