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	$168.45	11.515%	$187.847	$187.85	$187.85	$187.80
Purchase #2	$72.99	7.621%	$78.5526	$78.55	$78.55	$78.60
Purchase #3	$81.27	6.553%	$86.5956	$86.60	$86.60	$86.60
Purchase #4	$119.64	6.423%	$127.3245	$127.32	$127.30	$127.30
Purchase #5	$207.57	5.860%	$219.7336	$219.73	$219.75	$219.70
Purchase #6	$220.96	10.519%	$244.2028	$244.20	$244.20	$244.20
Purchase #7	$140.47	13.104%	$158.8772	$158.88	$158.90	$158.90
7 purchase totals =	$1,011.35		$1,103.1333	$1,103.13	$1,103.15	$1,103.10