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	$41.76	10.388%	$46.098	$46.10	$46.10	$46.10
Purchase #2	$213.75	7.506%	$229.7941	$229.79	$229.80	$229.80
Purchase #3	$67.43	6.844%	$72.0449	$72.04	$72.05	$72.00
Purchase #4	$40.69	13.290%	$46.0977	$46.10	$46.10	$46.10
Purchase #5	$215.93	8.253%	$233.7507	$233.75	$233.75	$233.80
Purchase #6	$224.35	7.385%	$240.9182	$240.92	$240.90	$240.90
Purchase #7	$89.55	11.326%	$99.6924	$99.69	$99.70	$99.70
7 purchase totals =	$893.46		$968.3960	$968.39	$968.40	$968.40