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	$207.45	3.404%	$214.5116	$214.51	$214.50	$214.50
Purchase #2	$76.38	4.363%	$79.7125	$79.71	$79.70	$79.70
Purchase #3	$219.33	11.427%	$244.3928	$244.39	$244.40	$244.40
Purchase #4	$81.72	11.220%	$90.889	$90.89	$90.90	$90.90
Purchase #5	$95.95	7.487%	$103.1338	$103.13	$103.15	$103.10
Purchase #6	$184.41	10.298%	$203.4005	$203.40	$203.40	$203.40
Purchase #7	$119.82	8.497%	$130.0011	$130.00	$130.00	$130.00
7 purchase totals =	$985.06		$1,066.0413	$1,066.03	$1,066.05	$1,066.00