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	$196.51	12.803%	$221.6692	$221.67	$221.65	$221.70
Purchase #2	$10.79	5.268%	$11.3584	$11.36	$11.35	$11.40
Purchase #3	$20.61	10.738%	$22.8231	$22.82	$22.80	$22.80
Purchase #4	$30.91	5.359%	$32.5665	$32.57	$32.55	$32.60
Purchase #5	$167.49	5.828%	$177.2513	$177.25	$177.25	$177.30
Purchase #6	$44.68	3.825%	$46.389	$46.39	$46.40	$46.40
Purchase #7	$83.36	7.801%	$89.8629	$89.86	$89.85	$89.90
7 purchase totals =	$554.35		$601.9204	$601.92	$601.85	$602.10