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	$59.97	3.534%	$62.0893	$62.09	$62.10	$62.10
Purchase #2	$78.66	5.621%	$83.0815	$83.08	$83.10	$83.10
Purchase #3	$13.52	4.786%	$14.1671	$14.17	$14.15	$14.20
Purchase #4	$27.31	3.871%	$28.3672	$28.37	$28.35	$28.40
Purchase #5	$155.33	6.673%	$165.6952	$165.70	$165.70	$165.70
Purchase #6	$159.94	13.239%	$181.1145	$181.11	$181.10	$181.10
Purchase #7	$182.59	9.557%	$200.0401	$200.04	$200.05	$200.00
7 purchase totals =	$677.32		$734.5549	$734.56	$734.55	$734.60