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	$78.64	4.306%	$82.0262	$82.03	$82.05	$82.00
Purchase #2	$206.65	11.197%	$229.7886	$229.79	$229.80	$229.80
Purchase #3	$75.85	3.555%	$78.5465	$78.55	$78.55	$78.50
Purchase #4	$59.59	4.517%	$62.2817	$62.28	$62.30	$62.30
Purchase #5	$142.54	13.773%	$162.172	$162.17	$162.15	$162.20
Purchase #6	$215.71	11.454%	$240.4174	$240.42	$240.40	$240.40
Purchase #7	$231.68	9.514%	$253.722	$253.72	$253.70	$253.70
7 purchase totals =	$1,010.66		$1,108.9544	$1,108.96	$1,108.95	$1,108.90