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	$102.61	13.162%	$116.1155	$116.12	$116.10	$116.10
Purchase #2	$124.56	9.346%	$136.2014	$136.20	$136.20	$136.20
Purchase #3	$177.68	6.864%	$189.876	$189.88	$189.90	$189.90
Purchase #4	$228.40	6.814%	$243.9632	$243.96	$243.95	$244.00
Purchase #5	$150.92	12.472%	$169.7427	$169.74	$169.75	$169.70
Purchase #6	$79.76	13.468%	$90.5021	$90.50	$90.50	$90.50
Purchase #7	$192.25	4.278%	$200.4745	$200.47	$200.45	$200.50
7 purchase totals =	$1,056.18		$1,146.8754	$1,146.87	$1,146.85	$1,146.90