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	$180.60	9.597%	$197.9322	$197.93	$197.95	$197.90
Purchase #2	$54.56	9.841%	$59.9292	$59.93	$59.95	$59.90
Purchase #3	$220.58	9.502%	$241.5395	$241.54	$241.55	$241.50
Purchase #4	$130.84	10.483%	$144.556	$144.56	$144.55	$144.60
Purchase #5	$141.49	9.532%	$154.9768	$154.98	$155.00	$155.00
Purchase #6	$191.86	7.143%	$205.5646	$205.56	$205.55	$205.60
Purchase #7	$135.53	9.265%	$148.0869	$148.09	$148.10	$148.10
7 purchase totals =	$1,055.46		$1,152.5852	$1,152.59	$1,152.65	$1,152.60