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	$195.62	5.255%	$205.8998	$205.90	$205.90	$205.90
Purchase #2	$194.54	7.663%	$209.4476	$209.45	$209.45	$209.40
Purchase #3	$57.79	7.736%	$62.2606	$62.26	$62.25	$62.30
Purchase #4	$160.41	11.522%	$178.8924	$178.89	$178.90	$178.90
Purchase #5	$90.95	9.305%	$99.4129	$99.41	$99.40	$99.40
Purchase #6	$196.36	12.702%	$221.3016	$221.30	$221.30	$221.30
Purchase #7	$88.50	4.225%	$92.2391	$92.24	$92.25	$92.20
7 purchase totals =	$984.17		$1,069.4540	$1,069.45	$1,069.45	$1,069.40