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	$113.37	10.415%	$125.1775	$125.18	$125.20	$125.20
Purchase #2	$83.83	7.119%	$89.7979	$89.80	$89.80	$89.80
Purchase #3	$22.64	9.500%	$24.7908	$24.79	$24.80	$24.80
Purchase #4	$183.91	3.852%	$190.9942	$190.99	$191.00	$191.00
Purchase #5	$246.66	7.279%	$264.6144	$264.61	$264.60	$264.60
Purchase #6	$94.25	5.113%	$99.069	$99.07	$99.05	$99.10
Purchase #7	$204.47	8.538%	$221.9276	$221.93	$221.95	$221.90
7 purchase totals =	$949.13		$1,016.3714	$1,016.37	$1,016.40	$1,016.40