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	$72.50	13.469%	$82.265	$82.27	$82.25	$82.30
Purchase #2	$9.69	6.563%	$10.326	$10.33	$10.35	$10.30
Purchase #3	$79.99	11.386%	$89.0977	$89.10	$89.10	$89.10
Purchase #4	$115.60	11.614%	$129.0258	$129.03	$129.05	$129.00
Purchase #5	$230.84	4.389%	$240.9716	$240.97	$240.95	$241.00
Purchase #6	$224.97	9.240%	$245.7572	$245.76	$245.75	$245.80
Purchase #7	$240.87	9.647%	$264.1067	$264.11	$264.10	$264.10
7 purchase totals =	$974.46		$1,061.5500	$1,061.57	$1,061.55	$1,061.60