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	$169.53	3.463%	$175.4008	$175.40	$175.40	$175.40
Purchase #2	$113.38	4.480%	$118.4594	$118.46	$118.45	$118.50
Purchase #3	$211.52	12.647%	$238.2709	$238.27	$238.25	$238.30
Purchase #4	$68.53	11.621%	$76.4939	$76.49	$76.50	$76.50
Purchase #5	$60.79	11.716%	$67.9122	$67.91	$67.90	$67.90
Purchase #6	$168.49	13.358%	$190.9969	$191.00	$191.00	$191.00
Purchase #7	$138.71	3.318%	$143.3124	$143.31	$143.30	$143.30
7 purchase totals =	$930.95		$1,010.8465	$1,010.84	$1,010.80	$1,010.90