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	$44.86	3.383%	$46.3776	$46.38	$46.40	$46.40
Purchase #2	$93.61	3.474%	$96.862	$96.86	$96.85	$96.90
Purchase #3	$100.38	5.128%	$105.5275	$105.53	$105.55	$105.50
Purchase #4	$243.83	6.409%	$259.4571	$259.46	$259.45	$259.50
Purchase #5	$173.93	4.715%	$182.1308	$182.13	$182.15	$182.10
Purchase #6	$153.81	12.678%	$173.31	$173.31	$173.30	$173.30
Purchase #7	$89.56	10.592%	$99.0462	$99.05	$99.05	$99.00
7 purchase totals =	$899.98		$962.7112	$962.72	$962.75	$962.70