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	$172.37	7.126%	$184.6531	$184.65	$184.65	$184.70
Purchase #2	$90.70	10.441%	$100.17	$100.17	$100.15	$100.20
Purchase #3	$201.67	7.733%	$217.2651	$217.27	$217.25	$217.30
Purchase #4	$169.77	12.362%	$190.757	$190.76	$190.75	$190.80
Purchase #5	$73.51	12.142%	$82.4356	$82.44	$82.45	$82.40
Purchase #6	$103.75	5.234%	$109.1803	$109.18	$109.20	$109.20
Purchase #7	$177.46	7.338%	$190.482	$190.48	$190.50	$190.50
7 purchase totals =	$989.23		$1,074.9431	$1,074.95	$1,074.95	$1,075.10