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	$209.76	8.823%	$228.2671	$228.27	$228.25	$228.30
Purchase #2	$74.32	8.719%	$80.8	$80.80	$80.80	$80.80
Purchase #3	$66.35	11.553%	$74.0154	$74.02	$74.00	$74.00
Purchase #4	$64.72	10.610%	$71.5868	$71.59	$71.60	$71.60
Purchase #5	$207.63	7.116%	$222.405	$222.41	$222.40	$222.40
Purchase #6	$80.32	12.844%	$90.6363	$90.64	$90.65	$90.60
Purchase #7	$250.57	11.170%	$278.5587	$278.56	$278.55	$278.60
7 purchase totals =	$953.67		$1,046.2693	$1,046.29	$1,046.25	$1,046.30