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	$222.27	10.599%	$245.8284	$245.83	$245.85	$245.80
Purchase #2	$148.49	3.250%	$153.3159	$153.32	$153.30	$153.30
Purchase #3	$39.86	3.824%	$41.3842	$41.38	$41.40	$41.40
Purchase #4	$172.66	10.542%	$190.8618	$190.86	$190.85	$190.90
Purchase #5	$151.26	6.704%	$161.4005	$161.40	$161.40	$161.40
Purchase #6	$90.63	11.460%	$101.0162	$101.02	$101.00	$101.00
Purchase #7	$247.58	6.765%	$264.3288	$264.33	$264.35	$264.30
7 purchase totals =	$1,072.75		$1,158.1358	$1,158.14	$1,158.15	$1,158.10