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	$244.30	7.623%	$262.923	$262.92	$262.90	$262.90
Purchase #2	$198.41	11.696%	$221.616	$221.62	$221.60	$221.60
Purchase #3	$192.91	9.807%	$211.8287	$211.83	$211.85	$211.80
Purchase #4	$123.42	4.825%	$129.375	$129.38	$129.40	$129.40
Purchase #5	$73.80	6.763%	$78.7911	$78.79	$78.80	$78.80
Purchase #6	$74.40	10.548%	$82.2477	$82.25	$82.25	$82.20
Purchase #7	$99.97	11.803%	$111.7695	$111.77	$111.75	$111.80
7 purchase totals =	$1,007.21		$1,098.5510	$1,098.56	$1,098.55	$1,098.50