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	$69.69	9.541%	$76.3391	$76.34	$76.35	$76.30
Purchase #2	$128.60	4.580%	$134.4899	$134.49	$134.50	$134.50
Purchase #3	$113.25	9.739%	$124.2794	$124.28	$124.30	$124.30
Purchase #4	$147.98	12.623%	$166.6595	$166.66	$166.65	$166.70
Purchase #5	$106.41	4.593%	$111.2974	$111.30	$111.30	$111.30
Purchase #6	$143.25	9.227%	$156.4677	$156.47	$156.45	$156.50
Purchase #7	$226.47	9.450%	$247.8714	$247.87	$247.85	$247.90
7 purchase totals =	$935.65		$1,017.4044	$1,017.41	$1,017.40	$1,017.50