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	$82.33	13.188%	$93.1877	$93.19	$93.20	$93.20
Purchase #2	$33.94	10.758%	$37.5913	$37.59	$37.60	$37.60
Purchase #3	$238.65	8.488%	$258.9066	$258.91	$258.90	$258.90
Purchase #4	$242.35	9.868%	$266.2651	$266.27	$266.25	$266.30
Purchase #5	$138.52	12.635%	$156.022	$156.02	$156.00	$156.00
Purchase #6	$99.79	9.114%	$108.8849	$108.88	$108.90	$108.90
Purchase #7	$90.81	11.403%	$101.1651	$101.17	$101.15	$101.20
7 purchase totals =	$926.39		$1,022.0227	$1,022.03	$1,022.00	$1,022.10