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	$175.79	5.503%	$185.4637	$185.46	$185.45	$185.50
Purchase #2	$35.25	4.369%	$36.7901	$36.79	$36.80	$36.80
Purchase #3	$236.98	10.707%	$262.3534	$262.35	$262.35	$262.40
Purchase #4	$247.44	4.505%	$258.5872	$258.59	$258.60	$258.60
Purchase #5	$114.83	12.809%	$129.5386	$129.54	$129.55	$129.50
Purchase #6	$66.43	7.738%	$71.5704	$71.57	$71.55	$71.60
Purchase #7	$156.57	10.114%	$172.4055	$172.41	$172.40	$172.40
7 purchase totals =	$1,033.29		$1,116.7089	$1,116.71	$1,116.70	$1,116.80