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	$160.27	4.525%	$167.5222	$167.52	$167.50	$167.50
Purchase #2	$42.46	13.791%	$48.3157	$48.32	$48.30	$48.30
Purchase #3	$140.34	11.470%	$156.437	$156.44	$156.45	$156.40
Purchase #4	$72.73	6.396%	$77.3818	$77.38	$77.40	$77.40
Purchase #5	$172.26	4.386%	$179.8153	$179.82	$179.80	$179.80
Purchase #6	$239.74	11.187%	$266.5597	$266.56	$266.55	$266.60
Purchase #7	$105.66	12.496%	$118.8633	$118.86	$118.85	$118.90
7 purchase totals =	$933.46		$1,014.8950	$1,014.90	$1,014.85	$1,014.90