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	$113.73	6.116%	$120.6857	$120.69	$120.70	$120.70
Purchase #2	$12.28	7.671%	$13.222	$13.22	$13.20	$13.20
Purchase #3	$121.33	5.394%	$127.8745	$127.87	$127.85	$127.90
Purchase #4	$120.76	11.591%	$134.7573	$134.76	$134.75	$134.80
Purchase #5	$60.71	4.563%	$63.4802	$63.48	$63.50	$63.50
Purchase #6	$69.37	3.150%	$71.5552	$71.56	$71.55	$71.60
Purchase #7	$171.29	13.535%	$194.4741	$194.47	$194.45	$194.50
7 purchase totals =	$669.47		$726.0490	$726.05	$726.00	$726.20