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	$176.38	10.303%	$194.5524	$194.55	$194.55	$194.60
Purchase #2	$136.79	3.165%	$141.1194	$141.12	$141.10	$141.10
Purchase #3	$35.50	10.731%	$39.3095	$39.31	$39.30	$39.30
Purchase #4	$9.63	9.231%	$10.5189	$10.52	$10.50	$10.50
Purchase #5	$240.59	10.169%	$265.0556	$265.06	$265.05	$265.10
Purchase #6	$149.67	10.349%	$165.1593	$165.16	$165.15	$165.20
Purchase #7	$181.89	4.786%	$190.5953	$190.60	$190.60	$190.60
7 purchase totals =	$930.45		$1,006.3104	$1,006.32	$1,006.25	$1,006.40