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	$237.68	4.577%	$248.5586	$248.56	$248.55	$248.60
Purchase #2	$14.26	11.153%	$15.8504	$15.85	$15.85	$15.90
Purchase #3	$18.40	9.300%	$20.1112	$20.11	$20.10	$20.10
Purchase #4	$129.67	11.509%	$144.5937	$144.59	$144.60	$144.60
Purchase #5	$135.72	10.760%	$150.3235	$150.32	$150.30	$150.30
Purchase #6	$57.80	7.711%	$62.257	$62.26	$62.25	$62.30
Purchase #7	$79.58	3.557%	$82.4107	$82.41	$82.40	$82.40
7 purchase totals =	$673.11		$724.1051	$724.10	$724.05	$724.20