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	$207.48	7.754%	$223.568	$223.57	$223.55	$223.60
Purchase #2	$70.45	7.641%	$75.8331	$75.83	$75.85	$75.80
Purchase #3	$37.39	8.118%	$40.4253	$40.43	$40.45	$40.40
Purchase #4	$81.30	13.103%	$91.9527	$91.95	$91.95	$92.00
Purchase #5	$198.42	8.506%	$215.2976	$215.30	$215.30	$215.30
Purchase #6	$95.82	9.867%	$105.2746	$105.27	$105.25	$105.30
Purchase #7	$229.55	9.546%	$251.4628	$251.46	$251.45	$251.50
7 purchase totals =	$920.41		$1,003.8141	$1,003.81	$1,003.80	$1,003.90