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	$219.47	13.503%	$249.105	$249.11	$249.10	$249.10
Purchase #2	$42.63	6.180%	$45.2645	$45.26	$45.25	$45.30
Purchase #3	$216.33	3.460%	$223.815	$223.82	$223.80	$223.80
Purchase #4	$235.98	12.636%	$265.7984	$265.80	$265.80	$265.80
Purchase #5	$9.64	10.580%	$10.6599	$10.66	$10.65	$10.70
Purchase #6	$30.72	5.501%	$32.4099	$32.41	$32.40	$32.40
Purchase #7	$212.59	5.617%	$224.5312	$224.53	$224.55	$224.50
7 purchase totals =	$967.36		$1,051.5839	$1,051.59	$1,051.55	$1,051.60