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	$232.67	13.704%	$264.5551	$264.56	$264.55	$264.60
Purchase #2	$233.31	4.404%	$243.585	$243.59	$243.60	$243.60
Purchase #3	$119.73	3.510%	$123.9325	$123.93	$123.95	$123.90
Purchase #4	$172.86	13.688%	$196.5211	$196.52	$196.50	$196.50
Purchase #5	$138.69	11.567%	$154.7323	$154.73	$154.75	$154.70
Purchase #6	$162.55	12.766%	$183.3011	$183.30	$183.30	$183.30
Purchase #7	$214.65	6.489%	$228.5786	$228.58	$228.60	$228.60
7 purchase totals =	$1,274.46		$1,395.2057	$1,395.21	$1,395.25	$1,395.20