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	$81.47	9.385%	$89.116	$89.12	$89.10	$89.10
Purchase #2	$6.56	9.387%	$7.1758	$7.18	$7.20	$7.20
Purchase #3	$55.76	12.418%	$62.6843	$62.68	$62.70	$62.70
Purchase #4	$233.25	10.670%	$258.1378	$258.14	$258.15	$258.10
Purchase #5	$245.71	7.714%	$264.6641	$264.66	$264.65	$264.70
Purchase #6	$170.82	6.337%	$181.6449	$181.64	$181.65	$181.60
Purchase #7	$185.89	12.722%	$209.5389	$209.54	$209.55	$209.50
7 purchase totals =	$979.46		$1,072.9618	$1,072.96	$1,073.00	$1,072.90