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	$219.66	11.452%	$244.8155	$244.82	$244.80	$244.80
Purchase #2	$52.95	3.716%	$54.9176	$54.92	$54.90	$54.90
Purchase #3	$85.32	8.482%	$92.5568	$92.56	$92.55	$92.60
Purchase #4	$148.36	12.172%	$166.4184	$166.42	$166.40	$166.40
Purchase #5	$221.91	3.365%	$229.3773	$229.38	$229.40	$229.40
Purchase #6	$200.49	6.104%	$212.7279	$212.73	$212.75	$212.70
Purchase #7	$153.77	9.610%	$168.5473	$168.55	$168.55	$168.50
7 purchase totals =	$1,082.46		$1,169.3608	$1,169.38	$1,169.35	$1,169.30