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	$198.69	3.464%	$205.5726	$205.57	$205.55	$205.60
Purchase #2	$233.98	6.469%	$249.1162	$249.12	$249.10	$249.10
Purchase #3	$219.67	11.684%	$245.3362	$245.34	$245.35	$245.30
Purchase #4	$41.68	5.312%	$43.894	$43.89	$43.90	$43.90
Purchase #5	$50.77	3.657%	$52.6267	$52.63	$52.65	$52.60
Purchase #6	$74.68	10.460%	$82.4915	$82.49	$82.50	$82.50
Purchase #7	$5.39	13.321%	$6.108	$6.11	$6.10	$6.10
7 purchase totals =	$824.86		$885.1452	$885.15	$885.15	$885.10