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	$78.40	9.463%	$85.819	$85.82	$85.80	$85.80
Purchase #2	$229.47	11.447%	$255.7374	$255.74	$255.75	$255.70
Purchase #3	$74.55	7.600%	$80.2158	$80.22	$80.20	$80.20
Purchase #4	$143.36	5.459%	$151.186	$151.19	$151.20	$151.20
Purchase #5	$219.34	10.338%	$242.0154	$242.02	$242.00	$242.00
Purchase #6	$90.40	9.772%	$99.2339	$99.23	$99.25	$99.20
Purchase #7	$141.87	11.531%	$158.229	$158.23	$158.25	$158.20
7 purchase totals =	$977.39		$1,072.4365	$1,072.45	$1,072.45	$1,072.30