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	$194.60	4.860%	$204.0576	$204.06	$204.05	$204.10
Purchase #2	$83.97	5.471%	$88.564	$88.56	$88.55	$88.60
Purchase #3	$168.56	7.540%	$181.2694	$181.27	$181.25	$181.30
Purchase #4	$49.27	10.629%	$54.5069	$54.51	$54.50	$54.50
Purchase #5	$192.69	11.393%	$214.6432	$214.64	$214.65	$214.60
Purchase #6	$64.54	12.775%	$72.785	$72.79	$72.80	$72.80
Purchase #7	$199.79	3.262%	$206.3071	$206.31	$206.30	$206.30
7 purchase totals =	$953.42		$1,022.1332	$1,022.14	$1,022.10	$1,022.20