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	$160.94	7.339%	$172.7514	$172.75	$172.75	$172.80
Purchase #2	$80.38	4.373%	$83.895	$83.90	$83.90	$83.90
Purchase #3	$55.93	7.138%	$59.9223	$59.92	$59.90	$59.90
Purchase #4	$169.70	7.658%	$182.6956	$182.70	$182.70	$182.70
Purchase #5	$204.32	10.253%	$225.2689	$225.27	$225.25	$225.30
Purchase #6	$119.62	6.356%	$127.223	$127.22	$127.20	$127.20
Purchase #7	$150.69	5.323%	$158.7112	$158.71	$158.70	$158.70
7 purchase totals =	$941.58		$1,010.4674	$1,010.47	$1,010.40	$1,010.50