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	$163.33	7.113%	$174.9477	$174.95	$174.95	$174.90
Purchase #2	$242.46	9.476%	$265.4355	$265.44	$265.45	$265.40
Purchase #3	$61.81	6.355%	$65.738	$65.74	$65.75	$65.70
Purchase #4	$150.42	7.242%	$161.3134	$161.31	$161.30	$161.30
Purchase #5	$85.33	11.848%	$95.4399	$95.44	$95.45	$95.40
Purchase #6	$52.87	7.405%	$56.785	$56.79	$56.80	$56.80
Purchase #7	$78.72	5.191%	$82.8064	$82.81	$82.80	$82.80
7 purchase totals =	$834.94		$902.4659	$902.48	$902.50	$902.30