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	$213.83	7.664%	$230.2179	$230.22	$230.20	$230.20
Purchase #2	$48.87	10.180%	$53.845	$53.85	$53.85	$53.80
Purchase #3	$223.45	3.130%	$230.444	$230.44	$230.45	$230.40
Purchase #4	$147.44	13.497%	$167.34	$167.34	$167.35	$167.30
Purchase #5	$41.44	4.173%	$43.1693	$43.17	$43.15	$43.20
Purchase #6	$55.35	4.360%	$57.7633	$57.76	$57.75	$57.80
Purchase #7	$210.85	10.506%	$233.0019	$233.00	$233.00	$233.00
7 purchase totals =	$941.23		$1,015.7814	$1,015.78	$1,015.75	$1,015.70