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	$93.25	13.122%	$105.4863	$105.49	$105.50	$105.50
Purchase #2	$168.84	13.279%	$191.2603	$191.26	$191.25	$191.30
Purchase #3	$229.92	3.586%	$238.1649	$238.16	$238.15	$238.20
Purchase #4	$204.79	13.793%	$233.0367	$233.04	$233.05	$233.00
Purchase #5	$165.76	9.404%	$181.3481	$181.35	$181.35	$181.30
Purchase #6	$190.27	3.812%	$197.5231	$197.52	$197.50	$197.50
Purchase #7	$46.53	6.266%	$49.4456	$49.45	$49.45	$49.40
7 purchase totals =	$1,099.36		$1,196.2650	$1,196.27	$1,196.25	$1,196.20