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	$76.82	8.133%	$83.0678	$83.07	$83.05	$83.10
Purchase #2	$80.91	5.451%	$85.3204	$85.32	$85.30	$85.30
Purchase #3	$152.38	3.834%	$158.2222	$158.22	$158.20	$158.20
Purchase #4	$208.81	10.202%	$230.1128	$230.11	$230.10	$230.10
Purchase #5	$56.45	4.731%	$59.1206	$59.12	$59.10	$59.10
Purchase #6	$215.82	6.220%	$229.244	$229.24	$229.25	$229.20
Purchase #7	$196.44	13.571%	$223.0989	$223.10	$223.10	$223.10
7 purchase totals =	$987.63		$1,068.1867	$1,068.18	$1,068.10	$1,068.10