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	$189.29	4.675%	$198.1393	$198.14	$198.15	$198.10
Purchase #2	$191.39	10.725%	$211.9166	$211.92	$211.90	$211.90
Purchase #3	$67.67	5.807%	$71.5996	$71.60	$71.60	$71.60
Purchase #4	$41.41	4.506%	$43.2759	$43.28	$43.30	$43.30
Purchase #5	$130.76	13.536%	$148.4597	$148.46	$148.45	$148.50
Purchase #6	$190.38	13.435%	$215.9576	$215.96	$215.95	$216.00
Purchase #7	$44.34	11.767%	$49.5575	$49.56	$49.55	$49.60
7 purchase totals =	$855.24		$938.9062	$938.92	$938.90	$939.00