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	$169.59	7.482%	$182.2787	$182.28	$182.30	$182.30
Purchase #2	$238.94	10.152%	$263.1972	$263.20	$263.20	$263.20
Purchase #3	$200.63	13.279%	$227.2717	$227.27	$227.25	$227.30
Purchase #4	$156.91	9.708%	$172.1428	$172.14	$172.15	$172.10
Purchase #5	$49.30	11.230%	$54.8364	$54.84	$54.85	$54.80
Purchase #6	$59.76	12.182%	$67.04	$67.04	$67.05	$67.00
Purchase #7	$91.34	3.277%	$94.3332	$94.33	$94.35	$94.30
7 purchase totals =	$966.47		$1,061.1000	$1,061.10	$1,061.15	$1,061.00