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	$197.98	11.254%	$220.2607	$220.26	$220.25	$220.30
Purchase #2	$53.59	12.506%	$60.292	$60.29	$60.30	$60.30
Purchase #3	$209.64	6.103%	$222.4343	$222.43	$222.45	$222.40
Purchase #4	$153.37	12.455%	$172.4722	$172.47	$172.45	$172.50
Purchase #5	$40.41	4.490%	$42.2244	$42.22	$42.20	$42.20
Purchase #6	$206.62	5.608%	$218.2072	$218.21	$218.20	$218.20
Purchase #7	$244.75	12.501%	$275.3462	$275.35	$275.35	$275.30
7 purchase totals =	$1,106.36		$1,211.2370	$1,211.23	$1,211.20	$1,211.20