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	$209.26	11.725%	$233.7957	$233.80	$233.80	$233.80
Purchase #2	$105.58	7.316%	$113.3042	$113.30	$113.30	$113.30
Purchase #3	$177.55	9.169%	$193.8296	$193.83	$193.85	$193.80
Purchase #4	$85.71	6.317%	$91.1243	$91.12	$91.10	$91.10
Purchase #5	$78.46	13.480%	$89.0364	$89.04	$89.05	$89.00
Purchase #6	$165.60	6.472%	$176.3176	$176.32	$176.30	$176.30
Purchase #7	$152.32	10.369%	$168.1141	$168.11	$168.10	$168.10
7 purchase totals =	$974.48		$1,065.5219	$1,065.52	$1,065.50	$1,065.40