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	$195.82	7.794%	$211.0822	$211.08	$211.10	$211.10
Purchase #2	$211.61	9.699%	$232.1341	$232.13	$232.15	$232.10
Purchase #3	$164.73	3.133%	$169.891	$169.89	$169.90	$169.90
Purchase #4	$214.77	8.782%	$233.6311	$233.63	$233.65	$233.60
Purchase #5	$168.96	11.532%	$188.4445	$188.44	$188.45	$188.40
Purchase #6	$93.46	12.841%	$105.4612	$105.46	$105.45	$105.50
Purchase #7	$54.68	9.177%	$59.698	$59.70	$59.70	$59.70
7 purchase totals =	$1,104.03		$1,200.3421	$1,200.33	$1,200.40	$1,200.30