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	$118.57	7.173%	$127.075	$127.08	$127.10	$127.10
Purchase #2	$54.67	6.849%	$58.4143	$58.41	$58.40	$58.40
Purchase #3	$54.38	7.470%	$58.4422	$58.44	$58.45	$58.40
Purchase #4	$108.88	9.273%	$118.9764	$118.98	$119.00	$119.00
Purchase #5	$151.64	13.599%	$172.2615	$172.26	$172.25	$172.30
Purchase #6	$94.97	4.792%	$99.521	$99.52	$99.50	$99.50
Purchase #7	$180.36	6.759%	$192.5505	$192.55	$192.55	$192.60
7 purchase totals =	$763.47		$827.2409	$827.24	$827.25	$827.30