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	$80.95	7.240%	$86.8108	$86.81	$86.80	$86.80
Purchase #2	$140.30	8.625%	$152.4009	$152.40	$152.40	$152.40
Purchase #3	$143.83	7.477%	$154.5842	$154.58	$154.60	$154.60
Purchase #4	$188.40	11.362%	$209.806	$209.81	$209.80	$209.80
Purchase #5	$56.68	4.585%	$59.2788	$59.28	$59.30	$59.30
Purchase #6	$164.44	4.664%	$172.1095	$172.11	$172.10	$172.10
Purchase #7	$157.82	12.829%	$178.0667	$178.07	$178.05	$178.10
7 purchase totals =	$932.42		$1,013.0569	$1,013.06	$1,013.05	$1,013.10