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	$168.31	3.764%	$174.6452	$174.65	$174.65	$174.60
Purchase #2	$45.97	3.778%	$47.7067	$47.71	$47.70	$47.70
Purchase #3	$11.68	3.415%	$12.0789	$12.08	$12.10	$12.10
Purchase #4	$141.74	13.243%	$160.5106	$160.51	$160.50	$160.50
Purchase #5	$96.59	13.271%	$109.4085	$109.41	$109.40	$109.40
Purchase #6	$127.83	4.454%	$133.5235	$133.52	$133.50	$133.50
Purchase #7	$105.89	7.439%	$113.7672	$113.77	$113.75	$113.80
7 purchase totals =	$698.01		$751.6406	$751.65	$751.60	$751.60