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	$99.49	11.789%	$111.2189	$111.22	$111.20	$111.20
Purchase #2	$44.92	6.102%	$47.661	$47.66	$47.65	$47.70
Purchase #3	$117.53	10.815%	$130.2409	$130.24	$130.25	$130.20
Purchase #4	$165.31	11.277%	$183.952	$183.95	$183.95	$184.00
Purchase #5	$205.86	4.482%	$215.0866	$215.09	$215.10	$215.10
Purchase #6	$234.86	8.696%	$255.2834	$255.28	$255.30	$255.30
Purchase #7	$156.73	5.382%	$165.1652	$165.17	$165.15	$165.20
7 purchase totals =	$1,024.70		$1,108.6080	$1,108.61	$1,108.60	$1,108.70