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	$146.35	10.868%	$162.2553	$162.26	$162.25	$162.30
Purchase #2	$174.91	5.542%	$184.6035	$184.60	$184.60	$184.60
Purchase #3	$243.87	4.805%	$255.588	$255.59	$255.60	$255.60
Purchase #4	$15.39	13.116%	$17.4086	$17.41	$17.40	$17.40
Purchase #5	$183.41	3.243%	$189.358	$189.36	$189.35	$189.40
Purchase #6	$53.56	13.307%	$60.6872	$60.69	$60.70	$60.70
Purchase #7	$246.89	11.591%	$275.507	$275.51	$275.50	$275.50
7 purchase totals =	$1,064.38		$1,145.4076	$1,145.42	$1,145.40	$1,145.50