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	$217.33	5.289%	$228.8246	$228.82	$228.80	$228.80
Purchase #2	$59.83	3.347%	$61.8325	$61.83	$61.85	$61.80
Purchase #3	$61.26	10.538%	$67.7156	$67.72	$67.70	$67.70
Purchase #4	$137.42	5.280%	$144.6758	$144.68	$144.70	$144.70
Purchase #5	$230.83	7.506%	$248.1561	$248.16	$248.15	$248.20
Purchase #6	$220.41	7.635%	$237.2383	$237.24	$237.25	$237.20
Purchase #7	$46.28	3.397%	$47.8521	$47.85	$47.85	$47.90
7 purchase totals =	$973.36		$1,036.2950	$1,036.30	$1,036.30	$1,036.30