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	$74.50	4.867%	$78.1259	$78.13	$78.15	$78.10
Purchase #2	$65.84	13.106%	$74.469	$74.47	$74.45	$74.50
Purchase #3	$122.55	10.567%	$135.4999	$135.50	$135.50	$135.50
Purchase #4	$219.59	8.526%	$238.3122	$238.31	$238.30	$238.30
Purchase #5	$67.32	6.527%	$71.714	$71.71	$71.70	$71.70
Purchase #6	$159.48	6.838%	$170.3852	$170.39	$170.40	$170.40
Purchase #7	$250.54	5.770%	$264.9962	$265.00	$265.00	$265.00
7 purchase totals =	$959.82		$1,033.5024	$1,033.51	$1,033.50	$1,033.50