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	$228.67	6.555%	$243.6593	$243.66	$243.65	$243.70
Purchase #2	$9.47	10.501%	$10.4644	$10.46	$10.45	$10.50
Purchase #3	$99.31	12.484%	$111.7079	$111.71	$111.70	$111.70
Purchase #4	$28.93	12.331%	$32.4974	$32.50	$32.50	$32.50
Purchase #5	$161.58	6.221%	$171.6319	$171.63	$171.65	$171.60
Purchase #6	$218.74	9.718%	$239.9972	$240.00	$240.00	$240.00
Purchase #7	$240.46	4.511%	$251.3072	$251.31	$251.30	$251.30
7 purchase totals =	$987.16		$1,061.2653	$1,061.27	$1,061.25	$1,061.30