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	$147.29	10.554%	$162.835	$162.84	$162.85	$162.80
Purchase #2	$80.48	4.150%	$83.8199	$83.82	$83.80	$83.80
Purchase #3	$43.83	10.202%	$48.3015	$48.30	$48.30	$48.30
Purchase #4	$250.45	3.585%	$259.4286	$259.43	$259.45	$259.40
Purchase #5	$171.95	3.168%	$177.3974	$177.40	$177.40	$177.40
Purchase #6	$245.58	7.137%	$263.107	$263.11	$263.10	$263.10
Purchase #7	$60.33	10.540%	$66.6888	$66.69	$66.70	$66.70
7 purchase totals =	$999.91		$1,061.5782	$1,061.59	$1,061.60	$1,061.50