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	$91.48	11.112%	$101.6453	$101.65	$101.65	$101.60
Purchase #2	$61.80	5.454%	$65.1706	$65.17	$65.15	$65.20
Purchase #3	$40.65	8.874%	$44.2573	$44.26	$44.25	$44.30
Purchase #4	$114.27	5.789%	$120.8851	$120.89	$120.90	$120.90
Purchase #5	$53.59	9.817%	$58.8509	$58.85	$58.85	$58.90
Purchase #6	$171.27	13.557%	$194.4891	$194.49	$194.50	$194.50
Purchase #7	$90.78	10.819%	$100.6015	$100.60	$100.60	$100.60
7 purchase totals =	$623.84		$685.8998	$685.91	$685.90	$686.00