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	$179.62	7.692%	$193.4364	$193.44	$193.45	$193.40
Purchase #2	$201.92	4.793%	$211.598	$211.60	$211.60	$211.60
Purchase #3	$168.38	4.802%	$176.4656	$176.47	$176.45	$176.50
Purchase #4	$46.27	9.111%	$50.4857	$50.49	$50.50	$50.50
Purchase #5	$173.41	4.243%	$180.7678	$180.77	$180.75	$180.80
Purchase #6	$131.82	9.609%	$144.4866	$144.49	$144.50	$144.50
Purchase #7	$97.72	7.498%	$105.047	$105.05	$105.05	$105.00
7 purchase totals =	$999.14		$1,062.2871	$1,062.31	$1,062.30	$1,062.30