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	$142.62	6.628%	$152.0729	$152.07	$152.05	$152.10
Purchase #2	$249.39	5.143%	$262.2161	$262.22	$262.20	$262.20
Purchase #3	$76.33	8.685%	$82.9593	$82.96	$82.95	$83.00
Purchase #4	$222.96	3.307%	$230.3333	$230.33	$230.35	$230.30
Purchase #5	$224.82	6.213%	$238.7881	$238.79	$238.80	$238.80
Purchase #6	$162.47	6.380%	$172.8356	$172.84	$172.85	$172.80
Purchase #7	$147.39	3.745%	$152.9098	$152.91	$152.90	$152.90
7 purchase totals =	$1,225.98		$1,292.1151	$1,292.12	$1,292.10	$1,292.10