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	$86.30	9.539%	$94.5322	$94.53	$94.55	$94.50
Purchase #2	$130.37	5.485%	$137.5208	$137.52	$137.50	$137.50
Purchase #3	$42.73	11.340%	$47.5756	$47.58	$47.60	$47.60
Purchase #4	$156.31	5.814%	$165.3979	$165.40	$165.40	$165.40
Purchase #5	$241.33	6.407%	$256.792	$256.79	$256.80	$256.80
Purchase #6	$205.26	8.178%	$222.0462	$222.05	$222.05	$222.00
Purchase #7	$196.29	11.633%	$219.1244	$219.12	$219.10	$219.10
7 purchase totals =	$1,058.59		$1,142.9891	$1,142.99	$1,143.00	$1,142.90