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	$45.60	5.415%	$48.0692	$48.07	$48.05	$48.10
Purchase #2	$10.36	7.583%	$11.1456	$11.15	$11.15	$11.10
Purchase #3	$142.88	6.696%	$152.4472	$152.45	$152.45	$152.40
Purchase #4	$99.57	6.539%	$106.0809	$106.08	$106.10	$106.10
Purchase #5	$78.50	6.231%	$83.3913	$83.39	$83.40	$83.40
Purchase #6	$198.43	12.740%	$223.71	$223.71	$223.70	$223.70
Purchase #7	$250.67	8.143%	$271.0821	$271.08	$271.10	$271.10
7 purchase totals =	$826.01		$895.9263	$895.93	$895.95	$895.90