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	$209.76	13.729%	$238.558	$238.56	$238.55	$238.60
Purchase #2	$74.38	11.391%	$82.8526	$82.85	$82.85	$82.90
Purchase #3	$158.90	6.815%	$169.729	$169.73	$169.75	$169.70
Purchase #4	$236.26	12.501%	$265.7949	$265.79	$265.80	$265.80
Purchase #5	$53.29	4.117%	$55.4839	$55.48	$55.50	$55.50
Purchase #6	$107.28	3.843%	$111.4028	$111.40	$111.40	$111.40
Purchase #7	$59.25	6.189%	$62.917	$62.92	$62.90	$62.90
7 purchase totals =	$899.12		$986.7382	$986.73	$986.75	$986.80