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	$199.97	7.573%	$215.1137	$215.11	$215.10	$215.10
Purchase #2	$57.77	6.253%	$61.3824	$61.38	$61.40	$61.40
Purchase #3	$80.81	12.375%	$90.8102	$90.81	$90.80	$90.80
Purchase #4	$143.25	7.528%	$154.0339	$154.03	$154.05	$154.00
Purchase #5	$244.31	10.631%	$270.2826	$270.28	$270.30	$270.30
Purchase #6	$181.65	8.792%	$197.6207	$197.62	$197.60	$197.60
Purchase #7	$31.67	5.194%	$33.3149	$33.31	$33.30	$33.30
7 purchase totals =	$939.43		$1,022.5584	$1,022.54	$1,022.55	$1,022.50