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	$162.73	4.658%	$170.31	$170.31	$170.30	$170.30
Purchase #2	$95.58	6.220%	$101.5251	$101.53	$101.55	$101.50
Purchase #3	$133.75	12.566%	$150.557	$150.56	$150.55	$150.60
Purchase #4	$175.87	5.801%	$186.0722	$186.07	$186.05	$186.10
Purchase #5	$233.69	3.253%	$241.2919	$241.29	$241.30	$241.30
Purchase #6	$212.98	10.594%	$235.5431	$235.54	$235.55	$235.50
Purchase #7	$98.27	13.470%	$111.507	$111.51	$111.50	$111.50
7 purchase totals =	$1,112.87		$1,196.8063	$1,196.81	$1,196.80	$1,196.80