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	$184.78	11.537%	$206.0981	$206.10	$206.10	$206.10
Purchase #2	$187.34	9.733%	$205.5738	$205.57	$205.55	$205.60
Purchase #3	$62.55	9.155%	$68.2765	$68.28	$68.30	$68.30
Purchase #4	$42.37	7.109%	$45.3821	$45.38	$45.40	$45.40
Purchase #5	$202.97	13.114%	$229.5875	$229.59	$229.60	$229.60
Purchase #6	$73.28	6.681%	$78.1758	$78.18	$78.20	$78.20
Purchase #7	$172.29	5.442%	$181.666	$181.67	$181.65	$181.70
7 purchase totals =	$925.58		$1,014.7598	$1,014.77	$1,014.80	$1,014.90