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	$193.34	3.816%	$200.7179	$200.72	$200.70	$200.70
Purchase #2	$162.60	7.815%	$175.3072	$175.31	$175.30	$175.30
Purchase #3	$9.26	11.584%	$10.3327	$10.33	$10.35	$10.30
Purchase #4	$189.81	5.250%	$199.775	$199.78	$199.80	$199.80
Purchase #5	$123.93	11.284%	$137.9143	$137.91	$137.90	$137.90
Purchase #6	$35.28	8.335%	$38.2206	$38.22	$38.20	$38.20
Purchase #7	$241.88	3.305%	$249.8741	$249.87	$249.85	$249.90
7 purchase totals =	$956.10		$1,012.1418	$1,012.14	$1,012.10	$1,012.10