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	$197.69	6.738%	$211.0104	$211.01	$211.00	$211.00
Purchase #2	$181.28	7.421%	$194.7328	$194.73	$194.75	$194.70
Purchase #3	$50.26	5.736%	$53.1429	$53.14	$53.15	$53.10
Purchase #4	$173.65	13.111%	$196.4173	$196.42	$196.40	$196.40
Purchase #5	$158.93	13.210%	$179.9247	$179.92	$179.90	$179.90
Purchase #6	$166.47	13.158%	$188.3741	$188.37	$188.35	$188.40
Purchase #7	$104.52	8.398%	$113.2976	$113.30	$113.30	$113.30
7 purchase totals =	$1,032.80		$1,136.8998	$1,136.89	$1,136.85	$1,136.80